Bi-weekly Influenza Situation Update 13 January 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 3 2020 and week 1 of 2021 are presented in the table below. Influenza A and B are co-circulating in the region, at a very low level compared to previous year (Figure 1). It should be noted that several countries and areas have not reported in 2020. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 3 2020 to week 1 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 3 2020 to week 1 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (1) 121,004 847 Cambodia (52) 1,069 169 China (53) 518,248 17,379 Fiji (29) 287 29 Japan (51) - 2,070 Lao People's Democratic Republic (52) 2,379 117 Malaysia (52) 2,737 221 Mongolia (48) 4,974 859 New Caledonia (11) 126 11 New Zealand (37) 198 - Papua New Guinea - - Philippines (4) 75 8 Republic of Korea (6) 1,119 379 Singapore (53) 3,033 258 Viet Nam (50) 1,857 131 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient sentinel indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continue to decrease, lower than in previous seasons. Outpatient ILI Surveillance China (North) During Week 53 of 2020, the percentage of visits for ILI at national sentinel hospitals in Northern China was 3.1%, higher than last week (2.9%), lower than the same week of 2017 to 2019 (5.5%, 4.7% and 5.7%) (Figure 2). Mongolia During Week 52 of 2020, ILI activity in Mongolia has remained low and is below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2018-2020 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In Week 1 of 2021, the overall weekly ILI rate was 2.4 ILI cases per 1,000 outpatient visits, lower than the previous week with 2.5 ILI cases per 1,000 outpatient visits and below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In Week 52 of 2020, the number of cases reported weekly by sentinel hospital sites remained low in Japan. The peak this year is lower than the previous years, but the general trend was similar to that seen in previous seasons (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2010-2020 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to decrease in most of the countries and areas. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In Week 1 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.7 ILI cases per 1,000 consultations, which was higher than 0.4 ILI cases per 1,000 consultations recorded in the previous week (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 19.8 ILI cases per 1,000 consultations, which was lower than 20.3 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 53 of 2020, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.1%, higher than the previous week (2.9%), and lower than the same week of 2017 to 2019 (5.5%, 4.7%, and 5.7%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 53 of 2020, the average daily number of patients seeking treatment in polyclinics for ARI was 849 over 4 working days, which is significantly lower than the same time period in 2019 (Figure 9). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2017-2021 Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2019-2020 (Source: China National Influenza Center) (Source: Singapore Ministry of Health) Influenza Situation Update | 5 Lao PDR In Week 52 of 2020, the number of ILI cases presenting to sentinel sites was lower compared to the previous week and the same week of the previous year (Figure 10). Figure 10: Weekly number of ILI presentations at sentinel sites, 2016-2020, Lao PDR (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 53, 2020, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable and low since week 11, with a second peak between weeks 39-40 (Figure 11). The positivity rate peaked in week 40 (65.2%) and has remained at 0% for the last nine weeks. In the second half of the year all positive specimens were influenza A(H3N2) (Figure 12). Figure 11: Number of ILI cases at seven sentinel sites and influenza positivity rate by week, 2020, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) From 1 January to 29 November 2020, there have been 21,266 notifications of laboratory-confirmed influenza to the National Notifiable Diseases Surveillance System. The number of cases was lower than the five-year average and did not show a seasonal peak between July and October, as seen in past years (Figure 13). Figure 13: Australian notifications of laboratory confirmed influenza (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period last year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 53 of 2020, there was an increase in ILI cases in Niue, Samoa, and Tokelau (Figure 14). Figure 14: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet Bulletin) Influenza Situation Update | 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 27 January 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 3 2020 and week 3 of 2021 are presented in the table below. Influenza A and B are co-circulating in the region, at a very low level compared to the same time of the previous year (Figure 1). Caution should be taken when interpreting these data as reporting to FluNet in 2020 was interrupted in some countries/areas. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 3 2020 to week 3 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 5 2020 to week 3 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (3) 125,765 847 Cambodia (53*) 1,091 169 China (2) 558,287 17,635 Fiji (29*) 287 29 Japan (2) - 2,076 Lao People's Democratic Republic (52*) 2,379 117 Malaysia (52*) 2,737 221 Mongolia (1) 5,143 859 New Caledonia (53*) 657 11 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 366 30 Republic of Korea (6*) 1,119 379 Singapore (3) 3,198 258 Viet Nam (50*) 1,857 131 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient sentinel indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continue to decrease, lower than in previous seasons. Outpatient ILI Surveillance China (North) During Week 2 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.7%, higher than last week (2.5%), lower than the same week of 2018 to 2020 (5.5%, 5.4% and 5.2%) (Figure 2). Mongolia During Week 2 of 2021, ILI activity in Mongolia has remained low and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2018-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In Week 3 of 2021, the overall weekly ILI rate was 2.6 ILI cases per 1,000 outpatient visits, lower than the previous week with 2.4 ILI cases per 1,000 outpatient visits. The trend this season has not shown the expected increase and has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In Week 1 of 2021, the number of cases reported weekly by sentinel hospital sites remained low in Japan. The number of cases this year is lower than the previous years. (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2010-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to decrease in most of the countries and areas. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In Week 3 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.4 ILI cases per 1,000 consultations, which was lower than 0.5 ILI cases per 1,000 consultations recorded in the previous week and lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 19.0 ILI cases per 1,000 consultations, which was lower than 19.8 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 2 of 2020, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.5%, higher than the previous week (3.4%), and lower than the same week of 2018 to 2020 (6.0 % , 5.6 % and 6.0%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance (No update) In Week 53 of 2020, the average daily number of patients seeking treatment in polyclinics for ARI was 849 over 4 working days, which is significantly lower than the same time period in 2019 (Figure 9). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2017-2021 Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2019-2020 (Source: Singapore Ministry of Health) (Source: China National Influenza Center) Influenza Situation Update | 5 Lao PDR In Week 1 of 2021, the number of ILI cases presenting to sentinel sites was higher compared to the previous week but lower than the same week of the previous year (Figure 10). Figure 10: Weekly number of ILI presentations at sentinel sites, 2016-2021, Lao PDR (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 3, 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable and low since week 11, 2020, with a second peak between weeks 39-40, 2020 (Figure 11). The positivity rate peaked in week 40, 2020 (65.2%) and has remained at 0% for the last twelve weeks. In week 3, 2021, there were no positive specimens (Figure 12). Figure 11: Number of ILI cases at seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 13). Figure 13: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 2 of 2021, there was an increase in ILI cases observed in Cook Islands, Federated States of Micronesia, Fiji, Niue, Samoa,Palau, and Tokelau (Figure 14). Figure 14: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet Bulletin) Influenza Situation Update | 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Influenza Situation Update| 1 Bi-weekly Influenza Situation Update 10 February 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 5 2020 and week 5 of 2021 are presented in the table below. Influenza A and B are co-circulating, but the majority of cases reported in the past 6 weeks are Influenza B. The number of cases reported to FluNet is showing an increasing trend, but still at a lower level compared to the same time of the previous year (Figure 1). Caution should be taken when interpreting these data as reporting to FluNet in 2020 was interrupted in some countries/areas. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 5 2020 to week 5 2021 *Data available for 2020 Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (5) 126,294 678 Cambodia (4) 1,141 158 China (4) 540,438 6,644 Fiji (2) 388 28 Japan (4) - 1,290 Lao People's Democratic Republic (5) 2,665 141 Malaysia (52*) 2,529 144 Mongolia (4) 4,628 522 New Caledonia (53*) 639 9 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 274 10 Republic of Korea (6*) 486 141 Singapore (5) 2,972 89 Viet Nam (53*) 1,890 123 Influenza Situation Update| 2 Bi-weekly Influenza Situation Update 10 February 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 7 2020 to week 5 2021 (Source: WHO FLUNET) Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient sentinel indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continue to decrease, lower than in previous seasons. Outpatient ILI Surveillance China (North) During Week 4 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.4%, lower than the last week (2.6%) and lower than the same week of 2018 to 2020 (4.8%, 5.1% and 6.8%) (Figure 2). Mongolia During Week 3 of 2021, ILI activity in Mongolia has remained low and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update| 3 Bi-weekly Influenza Situation Update 10 February 2021 Republic of Korea In Week 5 of 2021, the overall weekly ILI rate was 1.9 ILI cases per 1,000 outpatient visits, lower than the previous week (2.3 ILI cases per 1,000 outpatient visits) and much lower than previous seasons. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). IL I/ 1, 00 0 O ut pa tie nt C on su lta tio n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In Week 3 of 2021, the number of cases reported weekly by sentinel hospital sites remained low in Japan. The number of cases this year is lower than the previous years (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update| 4 Bi-weekly Influenza Situation Update 10 February 2021 Countries/areas in the tropical zone ILI and influenza activity continued to decrease in most of the countries and areas. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In Week 5 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.5 ILI cases per 1,000 consultations, which was same as 0.5 ILI cases per 1,000 consultations recorded in the previous week and lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 13.2 ILI cases per 1,000 consultations, which was lower than 23.3 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 4 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.0%, lower than the previous week (3.4%), and lower than the same week of 2018 to 2020 5.7%, 5.4% and 7.4%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance (no update) In Week 53 of 2020, the average daily number of patients seeking treatment in polyclinics for ARI was 849 over 4 working days, which is significantly lower than the same time period in 2019 (Figure 9). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2017-2021 Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2019-2020 (Source: China National Influenza Center) (Source: Singapore Ministry of Health) Influenza Situation Update| 5 Bi-weekly Influenza Situation Update 10 February 2021 Lao PDR In Week 5 of 2021, the proportion of ILI cases presenting to sentinel sites was lower compared to the previous week. There is some fluctuation in the trend of 2021, but remains within the observed range for the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 5 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable with a second peak in positive cases seen in the middle of 2020. The positivity rate peaked in week 40, 2020 (65.2%) and has remained at 0% for the last 13 weeks. In week 5, 2021, there were no positive specimens (Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update| 6 Bi-weekly Influenza Situation Update 10 February 2021 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update| 7 Bi-weekly Influenza Situation Update 10 February 2021 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 5 of 2021, ILI cases remained low. There was a slight increase ILI cases in French Polynesia comparing to the same period in the previous year (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentimental sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update| 8 Bi-weekly Influenza Situation Update 10 February 2021 Global influenza situation updates Virological update Global update Others: Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 24 February 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 7 2020 and week 7 of 2021 are presented in the table below. Influenza A and B are co-circulating, but the majority of cases reported in the past 8 weeks are Influenza B. The number of cases reported to FluNet is showing a decreasing trend from week 5 and remains at a lower level compared to the same time of the previous year (Figure 1). Caution should be taken when interpreting these data as reporting to FluNet was interrupted in some countries/areas. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 7 2020 to week 7 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 9 2020 to week 7 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (6) 126,052 514 Cambodia (6) 1,124 144 China (6) 549,218 2,436 Fiji (4) 466 26 Japan (5) - 673 Lao People's Democratic Republic (5) 2,667 147 Malaysia (6) 2,827 86 Mongolia (4) 3,890 141 New Caledonia (53*) 603 1 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 189 5 Republic of Korea (6*) - - Singapore (5) 2,681 28 Viet Nam (3) 1,973 149 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During Week 6 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.6%, higher than the last week (2.0%) and lower than the same week of 2018 to 2020 (3.6%, 6.2% and 6.2%) (Figure 2). Mongolia During Week 5 of 2021, ILI activity in Mongolia has remained low and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In Week 7 of 2021, the overall weekly ILI rate was 1.9 ILI cases per 1,000 outpatient visits, same as the previous week (1.9 ILI cases per 1,000 outpatient visits) and much lower than previous seasons. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In Week 5 of 2021, the number of cases reported weekly by sentinel hospital sites remained low in Japan. The number of cases this year is much lower than the previous years (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In Week 7 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.7 ILI cases per 1,000 consultations, which was higher than 0.5 ILI cases per 1,000 consultations recorded in the previous week but still lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 11.4 ILI cases per 1,000 consultations, which was lower than 16.5 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 (Source: Hong Kong Centre for Health Protection) Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 4 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.2%, higher than the previous week (2.4%), and lower than the same week of 2018 to 2020 (4.6%, 6.8% and 5.9%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance (no update) In Week 53 of 2020, the average daily number of patients seeking treatment in polyclinics for ARI was 849 over 4 working days, which is significantly lower than the same time period in 2019 (Figure 9). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2019-2020 (Source: Singapore Ministry of Health) Influenza Situation Update | 5 Lao PDR In Week 6 of 2021, the proportion of ILI cases presenting to sentinel sites was higher compared to the previous week. There is some fluctuation in the trend of 2021, but it remains within the observed range for the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia (No update) In week 5 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable with a second peak in positive cases seen in the middle of 2020. The positivity rate peaked in week 40, 2020 (65.2%) and has remained at 0% for the last 13 weeks. In week 5, 2021, there were no positive specimens (Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 6 of 2021, ILI cases remained low. There was a slight increase seen in ILI cases reported in Fiji, French Polynesia and New Caledonia, compared to the same period in the previous year (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update | 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 10 March 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 9 2020 and week 9 of 2021 are presented in the table below. Influenza A and B are co-circulating, but the majority of cases reported in the past 10 weeks are Influenza B. The number of cases reported to FluNet has plateaued from week 6 to 8 and no specimens have been reported (Figure 1). Caution should be taken when interpreting these data as there may be reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 9 2020 to week 9 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 11 2020 to week 9 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (8) 126,486 385 Cambodia (6) 1,079 135 China (8) 561,690 1,904 Fiji (4) 433 21 Japan (7) - 296 Lao People's Democratic Republic (7) 2,898 187 Malaysia (6) 2,645 59 Mongolia (8) 3,327 24 New Caledonia (53*) 603 1 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 109 1 Republic of Korea (6*) - - Singapore (8) 2,658 23 Viet Nam (9) 1,941 144 Influenza Situation Update| 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 8 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 1.7%, lower than the last week (2.0%) and lower than the same week of 2018 to 2020 (3.6%, 2.9% and 4.4%) (Figure 2). Mongolia During week 7 of 2021, ILI activity in Mongolia has remained low as less than 10 cases per 10,000 population and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update| 3 Republic of Korea In week 9 of 2021, the overall weekly ILI rate was 1.2 ILI cases per 1,000 outpatient visits, lower than the previous week (2.0 ILI cases per 1,000 outpatient visits) and previous seasons. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In week 7 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not inline with usual trends and is much lower than the previous years (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update| 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In week 9 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.6 ILI cases per 1,000 consultations, which was same as 0.6 ILI cases per 1,000 consultations recorded in the previous week and also lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 6.2 ILI cases per 1,000 consultations, which was much lower than 11.1 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 8 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 2.2%, lower than the previous week (2.7%), and also lower than the same week of 2018 to 2020 (4.8%, 3.9% and 3.7%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance (no update) In Week 53 of 2020, the average daily number of patients seeking treatment in polyclinics for ARI was 849 over 4 working days, which is significantly lower than the same time period in 2019 (Figure 9). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China,2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2019-2020 (Source: Singapore Ministry of Health) Influenza Situation Update| 5 Lao PDR (No update) In Week 6 of 2021, the proportion of ILI cases presenting to sentinel sites was higher compared to the previous week. There is some fluctuation in the trend of 2021, but it remains within the observed range for the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 9 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable with a second peak in positive cases seen in the middle of 2020. The positivity rate peaked in week 40, 2020 (65.2%) and has remained at 0% for the last 18 weeks. In week 9, 2021, there were no positive specimens (Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 20 40 60 80 100 120 140 160 180 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 2 4 6 8 N u m b er o f C as es Week ILI Case Positivity rate Influenza Situation Update| 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update| 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 8 of 2021, ILI cases remained low. There is an increasing ILI trend in Federated States of Micronesia and French Polynesia (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update| 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 24 March 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 11 of 2020 and week 11 of 2021 are presented in the table below. Influenza A and B are co-circulating, and the majority of cases that had been reported were Influenza B between week 52 2020 and week 10 2021. The number of cases reported to FluNet dropped to less than 20 on week 11 (Figure 1) and caution should be taken when interpreting these data as there may be reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 11 2020 to week 11 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 13 2020 to week 11 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (10) 125,142 219 Cambodia (8) 1,079 123 China (10) 565,395 1,841 Fiji (4) 431 20 Japan (9) - 70 Lao People's Democratic Republic (11) 3,282 242 Malaysia (10) 2,573 31 Mongolia (10) 2,741 9 New Caledonia (53*) 563 - New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 49 1 Republic of Korea (6*) - - Singapore (10) 2,707 17 Viet Nam (10) 1,913 160 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 10 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 1.8%, higher than the last week (1.6%) and lower than the same week of 2018 to 2020 (2.6%, 3.0% and 2.9% respectively) (Figure 2). Mongolia During week 9 of 2021, ILI activity in Mongolia has been increasing since week 5 but remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In week 11 of 2021, the overall weekly ILI rate was 2.2 ILI cases per 1,000 outpatient visits, higher than the previous week (1.9 ILI cases per 1,000 outpatient visits) and previous seasons. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). ILI /1 ,0 00 O ut pa tie nt C on su lta tio n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In week 9 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not inline with usual trends and is much lower than the previous years (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In week 11 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.5 ILI cases per 1,000 consultations, which was lower than 0.6 ILI cases per 1,000 consultations recorded in the previous week and also lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 5.6 ILI cases per 1,000 consultations, which was much lower than 15.5 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 (Source: Hong Kong Centre for Health Protection) Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 10 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 24%, higher than the previous week (2.2%), but lower than the same week of 2018 to 2020 (3.7%, 4.1% and 2.9% respectively) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 9 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,294 over 5.5 working days, which is significantly lower than the same time period in 2020 (Figure 9). The overall positivity rate for influenza among ILI samples (n=241) in the community was 0.0% in the past 4 weeks. Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China,2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 5 Lao PDR In Week 11 of 2021, the proportion of ILI cases presenting to sentinel sites decreased compared to the previous week. There is some fluctuation in the trend of 2021, but it remains within the observed range for the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 11 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40 2020 (65.2%). In week 11, 2021, there were no positive specimens and the positivity rate remains very low since week 45 2020.(Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 20 40 60 80 100 120 140 160 180 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 2 4 6 8 10 Nu m be r o f C as es Week ILI Case Positivity rate Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 10 of 2021, ILI cases remained low. There is an increasing ILI trend in New Caledonia, Samoa, Vanuatu and Wallis & Futuna (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update | 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 7 April 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 13 of 2020 and week 13 of 2021 are presented in the table below. Influenza A and B are co-circulating, and the majority of cases that had been reported were Influenza B between week 52 2020 and week 12 2021. The number of cases reported to FluNet dropped to less than 20 on week 13 (Figure 1) and caution should be taken when interpreting these data as there may be reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 13 2020 to week 13 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 15 2020 to week 13 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (13) 120,053 64 Cambodia (11) 1,116 112 China (12) 572,257 1,992 Fiji (4) 395 11 Japan (11) - 15 Lao People's Democratic Republic (13) 3,494 257 Malaysia (10) 2,390 5 Mongolia (12) 2,033 5 New Caledonia (53*) 500 - New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 5 0 Republic of Korea (6*) - - Singapore (12) 2,578 7 Viet Nam (12) 1,862 160 Influenza Situation Update| 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 12 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.1%, high than the last week (2.0%), lower than the same week of 2018 to 2020(2.7%, 3.6% and 2.4%) (Figure 2). Mongolia During week 11 of 2021, ILI activity in Mongolia has been decreased and remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2017-2021 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update| 3 Republic of Korea In week 13 of 2021, the overall weekly ILI rate was 2.2 ILI cases per 1,000 outpatient visits, higher than the previous week (2.0 ILI cases per 1,000 outpatient visits) but it remains within the observed range for previous season. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In week 11 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not inline with usual trends and is much lower than the previous years (Figure 5) . Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update| 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In week 13 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.4 ILI cases per 1,000 consultations, which was lower than 0.5 ILI cases per 1,000 consultations recorded in the previous week and also lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 14.3 ILI cases per 1,000 consultations, which was higher than 6.2 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 12 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 2.9%, higher than the previous week (2.8%), lower than the same week of 2018 to 2019 (3.6% and 4.1%), higher than the same week of 2020(2.7%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 12 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,214 over 5.5 working days, which is significantly lower than the same time period in 2020 (Figure 9). The overall positivity rate for influenza among ILI samples (n=301) in the community was 0.0% in the past 4 weeks. Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China,2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update| 5 Lao PDR In Week 12 of 2021, the proportion of ILI cases presenting to sentinel sites decreased compared to the previous week. There is some fluctuation in the trend of 2021, but it remains lower compared to the range of 3-year average for past three weeks (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 13 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40 2020 (65.2%). In week 13, 2021, there were no positive specimens and the positivity rate remains very low since week 45 2020.(Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 20 40 60 80 100 120 140 160 180 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 2 4 6 8 10 12 N u m b er o f C as es Week ILI Case Positivity rate Influenza Situation Update| 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI (No update) In 2020, the average ILI consultaion rate at sentinel general practitioners for the seasonal period was 1.6 per 1000 consultations, four times lower than the five year average for the same period (8.1 per 1000 Consultations) (Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2020, 2015-2020 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update| 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 12 of 2021, ILI cases remained low. There is an increasing ILI trend in Fiji, Niue, Samoa and Wallis & Futuna (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update| 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 21 April 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 15 of 2020 and week 15 of 2021 are presented in the table below. Influenza A and B are co-circulating, and the majority of cases that had been reported were Influenza B between week 52 2020 and week 14 2021. The number of cases reported to FluNet dropped to less than 20 on week 15 (Figure 1) and caution should be taken when interpreting these data as there may be reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 15 2020 to week 15 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 17 2020 to week 15 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (15) 117,048 22 Cambodia (11) 1,070 108 China (14) 567,185 1,893 Fiji (4) 308 - Japan (14) - 8 Lao People's Democratic Republic (14) 3,607 260 Malaysia (13) 2,604 2 Mongolia (14) 1,853 0 New Caledonia (53*) 479 0 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 3 0 Republic of Korea (6*) - - Singapore (13) 2,443 1 Viet Nam (13) 1,842 162 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 14 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.1%, lower than the last week (2.2%), lower than the same week of 2018 and 2019 (2.5% and 4.0%), higher than the same week of 2020(2.0%) (Figure 2). Mongolia During week 13 of 2021, ILI activity in Mongolia has been decreased and remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2022 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In week 15 of 2021, the overall weekly ILI rate was 2.3 ILI cases per 1,000 outpatient visits, lower than the previous week (2.5 ILI cases per 1,000 outpatient visits) and it remains within the observed range for previous season. The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). ILI /1 ,0 00 O ut pa tie nt C on su lta tio n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In week 13 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not in line with usual trends and is much lower than the previous years (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Surveillance Hong Kong SAR (China) – ILI and hospital Surveillance In week 15 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.3 ILI cases per 1,000 consultations, which was lower than 0.4 ILI cases per 1,000 consultations recorded in the previous week and also lower than the previous two years (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 8.5 ILI cases per 1,000 consultations, which was lower than 11.0 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 14 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.0%, the same as the previous week (3.0%), lower than the same week of 2018 to 2019 (3.6% and 4.3%), higher than the same week of 2020 (2.2%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 14 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,245 over 5.5 working days, which is significantly lower than the same time period in 2020 (Figure 9). The overall positivity rate for influenza among ILI samples (n=264) in the community was 0.0% in the past 4 weeks. Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China,2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 5 Lao PDR In Week 15 of 2021, the proportion of ILI cases presenting to sentinel sites decreased compared to the previous week. There is some fluctuation in the trend of 2021, but it remains lower compared to the range of 3-year average for past six weeks (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 15 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40 2020 (65.2%). In week 15, 2021, there were no positive specimens and the positivity rate remains very low since week 45 2020.(Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 20 40 60 80 100 120 140 160 180 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 2 4 6 8 10 12 14 Nu m be r o f C as es Week ILI Case Positivity rate Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI In the year to date, there have been 200 notifications of laboratory-confirmed influenza to the National Notifiable Diseases Surveillance System. Number of cases was lower than the five year average but showing a weekly trend similar to that seen in past years(Figure 12). Figure 12: ILI presentations to sentinel general practitioners, by week, 2021, 2016-2021 Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, 0 (0%) of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 14 of 2021, ILI cases remained low. There is an increasing ILI trend in Samoa, Tuvalu and Vanuatu (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update | 8 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 5 May 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 17 of 2020 and week 17 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, However, the majority of cases reported from week 52 2020 to week 17 2021 have been Influenza B. The number of cases reported to FluNet dropped to less than 20 on week 17 (Figure 1), However, caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 17, 2020 to week 17, 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 17, 2020 to week 17, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (16) 114370 13 Cambodia (11) 1038 108 China (16) 601752 2877 Fiji (4) 308 - Japan (14) - 5 Lao People's Democratic Republic (17) 3816 269 Malaysia (15) 2703 2 Mongolia (15) 1668 0 New Caledonia (53*) 466 0 New Zealand (37*) 198 - Papua New Guinea - - Philippines (51*) 3 0 Republic of Korea (6*) - - Singapore (16) 2570 1 Viet Nam (15) 1809 162 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 16 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.3%, higher than the last week (2.2%), lower than the same week of 2018 and 2019 (2.4% and 3.6%), higher than the same week of 2020 (1.9%) (Figure 2). Mongolia During week 15 of 2021, ILI activity in Mongolia has decreased and remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Due to ongoing surge in COVID-19 cases, public health and social measures have been in place since 10 April including movement and travel restrictions and limitation on gatherings which which may have impact on the trends of other infectious diseases. Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2022 (Source: China National Influenza Center) Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Influenza Situation Update | 3 Republic of Korea In week 17 of 2021, the overall weekly ILI rate was 2.0 ILI cases per 1,000 outpatient visits, lower than the previous week (2.3 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). ILI /1 ,0 00 O ut pa tie nt C on su lta tio n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Sentinel influenza surveillance Japan In week 15 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 4 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 17 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.7 ILI cases per 1,000 consultations, which was higher than 0.5 ILI cases per 1,000 consultations recorded in the previous week and is similar to the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 8.6 ILI cases per 1,000 consultations, which was lower than 109 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 16 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.4%, higher than the previous week (3.1%), lower than the same week of 2018 to 2019 respectively (3.6% and 4.2%), higher than the same week of 2020 (2.4%) (Figure 8). Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 16 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,347 over 5.5 working days, which remains within the observed range for previous season in 2020 (Figure 9). Of 283 samples tested in the past 4 weeks, there have been no positive results. Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China,2017-2021 (Source: China National Influenza Center) Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 5 Lao PDR In Week 17 of 2021, the proportion of ILI cases presenting to sentinel sites increased compared to the previous week. Over the past 6 weeks, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Of note, the increasing trend in ILI presentations seen from week 15 coensides with an increase in the number of COVID-19 cases reported in Lao PDR. Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to 3 years average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia (No update) In week 15 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40, 2020 (65.2%). In week 15, 2021, there were no positive specimens and the positivity rate remains very low since week 45 2020 (Figure 11). Figure 11: Number of ILI cases at 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 0 20 40 60 80 100 120 140 160 180 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 2 4 6 8 10 12 14 Nu m be r o f C as es Week ILI Case Positivity rate Influenza Situation Update | 6 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 12 to 25 April 2021, there were 25 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 232 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reportedare lower than the five year average but showing a weekly trend similar to that seen in past years (Figure 12). Figure 12: ILI presentations to sentinel general practitioners by week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, none of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 7 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 16 of 2021, ILI cases remained low. There is an increasing ILI trend in Kiribati, Samoa and Tonga (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries (Source: PacNet bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update | 8 Global influenza situation updates: Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 19 May 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 19 of 2020 and week 19 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 52, 2020 to week 19, 2021 have been Influenza B. The number of cases reported to FluNet dropped to less than 20 on week 19 (Figure 1), However, caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 19, 2020 to week 19, 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 19, 2020 to week 19, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (18) 112135 6 Cambodia (14) 1083 108 China (17) 597393 3216 Fiji (4) 308 - Japan (17) - 4 Lao People's Democratic Republic (18) 3814 269 Malaysia (15) 2625 2 Mongolia (18) 1489 0 New Caledonia (53*) 459 0 New Zealand (37*) 198 - Papua New Guinea - - Philippines (16) 37 0 Republic of Korea (6*) - - Singapore (18) 2674 0 Viet Nam (17) 1846 162 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 17 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.4%, slightly higher than the previous week (2.3%). This was also higher during the same period in 2018 and 2020 (2.3% and 1.8%, respectively), yet lower in 2019 (3.2%) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 17 of 2021, ILI activity in Mongolia has decreased and remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Due to ongoing COVID-19 outbreak, public health and social measures have been in place since 10 April including movement and travel restrictions and limitation on gatherings which which may have impact on the trends of other infectious diseases. Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 19 of 2021, the overall weekly ILI rate was 2.1 ILI cases per 1,000 outpatient visits, which was higher than the previous week (1.8 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). ILI /1 ,0 00 O ut pa tie nt C on su lta tio n Week Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 17 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 19 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.3 ILI cases per 1,000 consultations, which was lower than 0.5 ILI cases per 1,000 consultations recorded in the previous week and is similar to the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 14.4 ILI cases per 1,000 consultations, which was higher than 10.7 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 17 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.7%, higher than the previous week (3.4%), higher than the same week of 2018 and 2020 (3.6% and 2.3%, respectively) and lower than the same week of 2019 (4.2%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2017-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 18 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,459 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 325 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0%; there were no positive results in April 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR From 1 to 7 May 2021, the proportion of ILI cases presenting to sentinel sites is less than the previous week. Over the past two months, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 18 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40, 2020 (65.2%). In week 18, 2021, there were no positive specimens and the positivity rate remains very low since week 45, 2020 (Figure 11). Influenza Situation Update | 7 Figure 11: Number of ILI cases from 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Cambodia Coronavirus Disease 2019 (COVID-19) Situation Report #45, World Health Organization) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 26 April to 9 May 2021, there were 13 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 240 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported are lower than the five-year average but showing a weekly trend similar to that seen in past years (Figure 12). Figure 12: ILI presentations to sentinel general practitioners by month and week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness (No update) General Practice-based ILI surveillance methods have changed in 2020 due to the COVID-19 response, limiting interpretability for influenza ILI surveillance. Collection of specimens commenced on 2nd June 2020 and stopped on 27 September 2020. In this period, there were 230 specimens collected from patients presenting to general practices with ILI symptoms, none of which were influenza positive. For the same period in the previous year, 1,617 specimens were tested, 919 (56.8%) of which were influenza positive. (Source) Influenza Situation Update | 9 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 18 of 2021, ILI cases overall remained low. However, there is an increasing ILI trend inthe Republic of the Marshall Islands and the Commonwealth of the Northern Mariana Islands(Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries, 3-9 May 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update | 10 Global influenza situation updates: Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Influenza Situation Update| 1 Bi-weekly Influenza Situation Update 2 June 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 23 of 2020 and week 21 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 52, 2020 to week 21, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 23, 2020 to week 21, 2021 *Data available for 2020 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 24, 2020 to week 20, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (21) 103730 6 Cambodia (14) 1001 108 China (20) 605991 4156 Fiji (4) 308 Japan (20) 6 Lao People's Democratic Republic (21) 3821 269 Malaysia (21) 2802 2 Mongolia (20) 1268 0 New Caledonia (53*) 395 0 New Zealand (37*) 198 Papua New Guinea Philippines (16) 37 0 Republic of Korea Singapore (20) 2771 0 Viet Nam (20) 1790 162 Influenza Situation Update| 2 Bi-weekly Influenza Situation Update 2 June 2021 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 20 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.7%, slightly higher than the previous week (2.4%). This was also higher during the same period in 2018, 2019, and 2020 (2.3%, 2.5% and 1.9%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update| 3 Bi-weekly Influenza Situation Update 2 June 2021 Mongolia During week 19 of 2021, ILI activity in Mongolia continues to decrease and remains lower than 20 cases per 10,000 population and below the lower tolerance limit (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 21 of 2021, the overall weekly ILI rate was 1.7 ILI cases per 1,000 outpatient visits, which was lower than the previous week (2.3 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) IL I ( p er 1 0, 0 00 p o p u la ti o n IL I ( p er 1 , 0 00 o u tp at ie n t co n su lt at io n Week Influenza Situation Update| 4 Bi-weekly Influenza Situation Update 2 June 2021 Sentinel influenza surveillance Japan In week 19 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year is not in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update| 5 Bi-weekly Influenza Situation Update 2 June 2021 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 21 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.7 ILI cases per 1,000 consultations, which was higher than 0.6 ILI cases per 1,000 consultations recorded in the previous week and is slightly lower to the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 10.8 ILI cases per 1,000 consultations, which was lower than 20.3 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 20 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 2.7%, higher than the previous week (2.4%), higher than the same week of 2018, 2019, and 2020 (2.3%, 2.5% and 1.9%, respectively) (4.2%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update| 6 Bi-weekly Influenza Situation Update 2 June 2021 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 20 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,669 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 346 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0%; there were no positive results in April 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR From 8 to 14 May 2021, the proportion of ILI cases presenting to sentinel sites is less than the previous week. Over the past two months, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia (no update) In week 18 of 2021, the number of ILI cases reported weekly by seven sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a second peak in positivity rate seen in week 40, 2020 (65.2%). In week 18, 2021, there were no positive specimens and the positivity rate remains very low since week 45, 2020 (Figure 11). Influenza Situation Update| 7 Bi-weekly Influenza Situation Update 2 June 2021 Figure 11: Number of ILI cases from 7 sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Cambodia Coronavirus Disease 2019 (COVID-19) Situation Report #45, World Health Organization) Influenza Situation Update| 8 Bi-weekly Influenza Situation Update 2 June 2021 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 10 May to 23 May 2021, there were 43 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 249 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported are lower than the five-year average but showing a weekly trend similar to that seen in past years (Figure 12). Figure 12: ILI presentations to sentinel general practitioners by month and week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. In the week ending 21 May 2021, there were no outbreaks of influenza-like illness, acute respiratory infections or COVID-19 reported. (Source) Influenza Situation Update| 9 Bi-weekly Influenza Situation Update 2 June 2021 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 20 of 2021, ILI cases overall remained low. However, there is an increasing ILI trend inthe Republic of the Marshall Islands, New Caledonia, and the Commonwealth of the Northern Mariana Islands. Cases in Samoa appear to be decreasing but numbers remain high (Figure 13). Figure 13: Reported cases of influenza-like illness in Pacific Island Countries, 17-23 May 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) * Caution should be taken in interpreting these data as there may be changes in number of sentinal sites reporting to the Pacific Syndromic Surveillance System. Influenza Situation Update| 10 Bi-weekly Influenza Situation Update 2 June 2021 Global influenza situation updates: Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link • WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2021 Southern Hemisphere Influenza Season Link • Antigenic and genetic characteristics of zoonotic influenza viruses and candidate vaccine viruses developed for potential use in human vaccines Link • 4th WHO Informal Consultation on Improving Influenza Vaccine Virus Selection Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 16 June 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 23 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 52, 2020 to week 23, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 23, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 25, 2020 to week 23, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (23) 37,281 1 Cambodia (14) 339 0 China (22) 326,333 4,633 Fiji (4) 222 - Japan (21) - 4 Lao People's Democratic Republic (23) 1,663 146 Malaysia (23) 1,230 0 Mongolia (21) 296 0 New Caledonia - - New Zealand - - Papua New Guinea - - Philippines (16) 9 0 Republic of Korea - - Singapore (22) 1,455 0 Viet Nam (20) 378 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 22 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 3.0%, slightly higher than the previous week (2.8%). This was also higher during the same period in 2018, 2019, and 2020 (2.4%, 2.4% and 1.9%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 21 of 2021, there was a slight increase in ILI activity in Mongolia at six ILI cases per 10,000 population. But this remains below the lower tolerance limit of seven ILI cases per 10,000 population. (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 23 of 2021, the overall weekly ILI rate was 1.9 ILI cases per 1,000 outpatient visits, which was higher than the previous week (1.8 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 21 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 23 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.4 ILI cases per 1,000 consultations, which was lower than the 0.7 ILI cases per 1,000 consultations recorded in the previous week and is lower than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 11.3 ILI cases per 1,000 consultations, which was slightly lower than 11.4 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 22 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 4.3%, higher than the previous week (4.2%), higher than the same week of 2018, 2019, and 2020 (4.2%, 4.1% and 2.9%, respectively) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 22 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 910 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 248 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%; there were no positive results in May 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR (no update) From 8 to 14 May 2021, the proportion of ILI cases presenting to sentinel sites is less than the previous week. Over the past two months, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Influenza Situation Update | 7 Cambodia In week 21 of 2021, the number of ILI cases reported weekly by sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a peak in positivity rate seen in week 40, 2020 (65.2%) (Figure 11). In week 21, 2021, there were no positive specimens and the positivity rate has remained very low since week 45, 2020. Influenza A was last detected in a sample in week 8, 2021 (Figure 12). Figure 11: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 24 May to 6 June 2021, there were 30 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 326 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported are lower than the five-year average but showing a weekly trend similar to that seen in past years (Figure 13). Figure 13: ILI presentations to sentinel general practitioners by month and week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. In the week ending on 4 June 2021, there were three ILI/ARI outbreaks reported in two early childhood education centres in Hawke’s Bay and in one early childhood education centre in Wellington. Overall, ILI consultation rates reported by HealthStat sentinel surveillance sites have been lower than the weekly rates seen at this time in 2020, and are following a similar trend to the historical rates (Figure 14). Figure 14: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Influenza Situation Update | 9 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 22 of 2021, ILI cases overall remained low. However, ILI cases increased in the Solomon Islands which may be due to an increase in the number of reporting sentinel sites. There was a decrease in ILI cases reported in Tuvalu, the Northern Mariana Islands, and Federated States of Micronesia. Decreases were also seen in Fiji, Tonga, Kiribati, and New Caledonia but these may due to a decreased number of sites reporting for the week (Figure 15). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 15: Reported cases of influenza-like illness in Pacific Island Countries, 31 May to 6 June 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 10 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 30 June 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 25 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 27, 2020 to week 25, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 25, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 27, 2020 to week 25, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (25) 42214 1 Cambodia (14) 339 0 China (24) 343907 5264 Fiji (4) 222 Japan (24) 4 Lao People's Democratic Republic (25) 1726 146 Malaysia (23) 1230 0 Mongolia (23) 296 0 New Caledonia New Zealand Papua New Guinea Philippines (16) 9 0 Republic of Korea Singapore (24) 1513 0 Viet Nam (25) 429 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 24 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.9%, lower than the previous week (3.2%) and higher during the same period in 2018-2020 (2.4%, 2.3% and 2.2%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 23 of 2021, ILI activity in Mongolia remained at six ILI cases per 10,000 population as recorded in the previous report. This is slightly higher than the lower tolerance limit of four ILI cases per 10,000 population. (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 25 of 2021, the overall weekly ILI rate was 1.2 ILI cases per 1,000 outpatient visits, which was lower than the previous week (1.3 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/ 1, 00 0 O u tp at ie n t C o n su lt at io n s WEEK Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 23 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 25 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.7 ILI cases per 1,000 consultations, which was higher than the 0.6 ILI cases per 1,000 consultations recorded in the previous week and the same rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 8.6 ILI cases per 1,000 consultations, which was higher than 6.9 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 24 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 4.2%, lower than the previous week (4.3%), higher than the same week of 2018 and 2020 (4.0% and 3.1%, respectively) and the same as the period of 2019 (4.2%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 24 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 720 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 133 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%; there were no positive results in May 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR (no update) From 8 to 14 May 2021, the proportion of ILI cases presenting to sentinel sites is less than the previous week. Over the past two months, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Influenza Situation Update | 7 Cambodia In week 24 of 2021, the percentage of ILI cases was 1.1% among all consultations. This was similar to the previous week (1%) and lower than the same week in 2020 (3.2%) (Figure 11). In week 24, 2021, there were no positive specimens for influenza A or B and the positivity rate; there has only been one Influenza A case detected for 2021 in week 8 (Figure 12). Figure 11: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 7 June to 20 June 2021, there were 27 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 358 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average but showing a weekly trend similar to that seen in past years (Figure 13). Figure 13: ILI presentations to sentinel general practitioners by month and week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. In the week ending on 18 June 2021, there were two ILI outbreaks reported at aged residential centres in Palmerston North (16 cases) and Dunedin (20 cases). There was an additional ARI outbreak in an aged residential centre in Wellington, resulting in 41 cases. Overall, ILI consultation rates reported by HealthStat sentinel surveillance sites have been lower than the weekly rates seen at this time in 2020, and are following a similar trend to the historical rates (Figure 14). Influenza Situation Update | 9 Figure 14: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 24 of 2021, ILI cases overall remained low. However, ILI cases increased in the Northern Mariana Islands, Wallis & Futuna, the Republic of the Marshall Islands and Solomon Islands. There was a decrease in ILI cases reported in Vanuatu, Fiki, Kiribati, New Caledonia and Palau. There were no changes to the number of ILI cases in the Cook Islands for the week. No ILI cases were availale from French Polynesia, Samoa and Tonga for the week. American Samoa, Guam and Nauru have not participated in the surveillance (Figure 15). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 15: Reported cases of influenza-like illness in Pacific Island Countries, 14 June to 20 June 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 10 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 14 July 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 27 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 29, 2020 to week 27, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 27, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 29, 2020 to week 27, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (26) 46 604 1 Cambodia (14) 339 0 China (26) 361 120 5664 Fiji (4) 222 Japan (25) 4 Lao People's Democratic Republic (27) 1795 146 Malaysia (25) 1415 1 Mongolia (23) 296 0 New Caledonia New Zealand Papua New Guinea Philippines (26) 190 11 Republic of Korea Singapore (26) 1574 0 Viet Nam (25) 429 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 26 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.6%, lower than the previous week (2.7%) and higher during the same period in 2018-2020 (2.3%, 2.4% and 2.2%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 25 of 2021, ILI activity in Mongolia remained at ten ILI cases per 10,000 population as recorded in the previous report. This is higher than the lower tolerance limit of two ILI cases per 10,000 population (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 27 of 2021, the overall weekly ILI rate was 1.4 ILI cases per 1,000 outpatient visits, which was lower than the previous week (1.9 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/ 1, 00 0 O u tp at ie n t C o n su lt at io n s WEEK Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 25 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 27 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.3 ILI cases per 1,000 consultations, which was lower than the 0.5 ILI cases per 1,000 consultations recorded in the previous week and slightly less than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 11.1 ILI cases per 1,000 consultations, which was higher than 7.3 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 26 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.8%, lower than the previous week (4.0%), higher than the same week of 2018 and 2020 (3.6% and 3.3%, respectively) and the same as the period of 2019 (4.0%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 26 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 798 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 119 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%; there were no positive results in May 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR (no update) From 8 to 14 May 2021, the proportion of ILI cases presenting to sentinel sites is less than the previous week. Over the past two months, ILI presentations have fluctuated compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Influenza Situation Update | 7 Cambodia In week 26 of 2021, the percentage of ILI cases was 1.1% among all consultations. This was similar to the previous week (1%) and lower than the same week in 2020 (3%) (Figure 11). In week 26, 2021, there were no positive specimens for influenza A or B and the positivity rate; there has only been one Influenza A case detected for 2021 in week 8 (Figure 12). Figure 11: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza and ILI From 21 June to 4 July 2021, there were 25 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 388 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average but showing a weekly trend similar to that seen in past years (Figure 13). Figure 13: ILI presentations to sentinel general practitioners by month and week from 2016-2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, ILI levels continued to increase in the week ending 4 July 2021. There is still no influenza virus detected through the surveillance system. Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. In the week ending 4 July 2021, there were five ILI or ARI outbreaks reported: four in Auckland (2 ECE and 2 ARC) and one in Wellington (ECE). Test results are pending (Figure 14). Figure 14: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Influenza Situation Update | 9 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 26 of 2021, actual increases in the number of ILI cases is seen in Fiji, Wallis & Futuna, Vanuatu, CNMI and Cook Islands. The increase seen in Vanuatu may due to increased number of sites reported for the week. Reduction of ILI cases were seen in Solomon Islands and RMI. The decrease seen in Solomon Islands may due to decreased number of sites reported for the week. There was no changes to number of ILI cases in Tonga for the week. No ILI cases reported for the week from Palau, Pitcairn Islands and Tokelau. No reports were available from French Polynesia, Samoa, Tuvalu, Niue, FSM, Kiribati and New Caledonia for the week. American Samoa, Guam and Nauru, have not participated in the surveillance (Figure 15). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 15: Reported cases of influenza-like illness in Pacific Island Countries, 28 June to 4 July 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 10 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 28 July 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 29 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 31, 2020 to week 29, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 29, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 31, 2020 to week 29, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (28) 51387 1 Cambodia (14) 339 0 China (28) 378078 6086 Fiji (4) 222 - Japan (25) - 4 Lao People's Democratic Republic (28) 1826 146 Malaysia (27) 1520 1 Mongolia (25) 300 0 New Caledonia - - New Zealand - - Papua New Guinea - - Philippines (29) 286 40 Republic of Korea - - Singapore (28) 1664 1 Viet Nam (29) 435 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 28 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.4%, lower than the previous week (2.5%) and higher during the same period in 2018-2020 (2.2%, 2.3% and 1.9%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 27 of 2021, there was a slight decrease in ILI activity in Mongolia at four ILI cases per 10,000 population as recorded in the previous report. This is higher than the lower tolerance limit of one ILI case per 10,000 population (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 29 of 2021, the overall weekly ILI rate was 1.9 ILI cases per 1,000 outpatient visits, which was slightly higher than the previous week (1.7 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold ILI /1 ,0 00 O ut pa tie nt C on su lta tio ns 2020-2021 Seasonal threshold Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 26 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 29 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.5 ILI cases per 1,000 consultations, which was higher than the 0.3 ILI cases per 1,000 consultations recorded in the previous week and slightly less than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 10.8 ILI cases per 1,000 consultations, which was higher than 10.5 recorded in the previous week (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During Week 28 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.6%, lower than the previous week (3.7%), higher than the same week of 2018 and 2020 (3.2% and 2.7%, respectively) and the same as the period of 2019 (3.7%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In Week 28 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,024 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 151 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.7%; there were no positive results in June 2021. Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR (no update) From 10 to 16 July 2021, the proportion of ILI cases presenting to sentinel sites is higher than the previous week. Over the past two months, ILI presentations have been lower compared to the 3-year average (Figure 10). Figure 10: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Influenza Situation Update | 7 Cambodia In week 27 of 2021, the percentage of ILI cases was 0.4% among all consultations. This was similar to the previous week (1%) and the same week in 2020 (1%) (Figure 11). In week 27, 2021, there were no positive specimens for influenza A or B and the positivity rate; there has only been one Influenza A case detected for 2021 in week 8 (Figure 12). Figure 11: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 12: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 5 July to 18 July 2021, there were 27 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 419 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average and showing a weekly trend similar to that seen in 2020 (Figure 13). Figure 13: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, ILI levels has decreased in the week ending 18 July 2021 (Figure 14). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are still no influenza virus detected through the surveillance system in 2021. . Figure 14: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Influenza Situation Update | 9 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 28 of 2021, increases in the number of ILI cases has been seen in Palau, New Caledonia, the Federated States of Micronesia, Solomon Islands and the Marshall Islands. The increase seen in Tonga may be due to increased number of sites reported for the week. Reduction of ILI cases have been seen in Kiribati, Vanuatu, Wallis & Futuna and Tuvalu. (Figure 15). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 15: Reported cases of influenza-like illness in Pacific Island Countries, 12 July to 18 July 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 10 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 11 August 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 31 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 31, 2020 to week 29, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 31, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 33, 2020 to week 31, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (31) 55386 3 Cambodia (14) 339 0 China (30) 394883 6537 Fiji (4) 222 Japan (30) 4 Lao People's Democratic Republic (30) 1919 146 Malaysia (27) 1805 1 Mongolia (25) 300 0 New Caledonia New Zealand Papua New Guinea Philippines (29) 322 40 Republic of Korea Singapore (30) 1761 1 Viet Nam (30) 497 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 30 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.4%, the same as last week (2.4%), and higher than the same period in 2018-2020 (2.2%, 2.2% and 2.0%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 29 of 2021, there was a slight increase in ILI activity in Mongolia at seven ILI cases per 10,000 population as recorded in the previous report. This is higher than the lower tolerance limit of zero ILI case per 10,000 population, yet lower than the upper tolerance limit of 18 per 10,000 population (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 31 of 2021, the overall weekly ILI rate was 1.2 ILI cases per 1,000 outpatient visits, which was slightly lower than the previous week (1.7 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n s 2020-2021 Seasonal threshold Week Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 29 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peaks (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 31 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.5 ILI cases per 1,000 consultations, which was the same as 0.5 ILI cases per 1,000 consultations recorded in the previous week and slightly less than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 6.4 ILI cases per 1,000 consultations, which was lower than 10.1 recorded in the previous week and the lowest ILI rate recorded during the same period from 2017 to current (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During week 30 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.3%, lower than the previous week (3.4%), higher than the same week of 2018 and 2020 (3.1% and 2.7%, respectively) and lower than during the same period in 2019 (3.5%) (Figure 8). Influenza Situation Update | 6 Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Singapore – Acute Respiratory Infection (ARI) Surveillance In week 30 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1,109 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 187 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.5%; the specimen that tested positive for influenza in July 2021 was positive for influenza B (Figure 10). Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 7 Figure 10: Monthly influenza surveillance for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR From 24 to 30 July 2021, the proportion of ILI cases presenting to sentinel sites is higher than the previous week. Over the past two months, ILI presentations have been lower compared to the 3- year average (Figure 11). Figure 11: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 30 of 2021, the number of ILI cases reported weekly by sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a peak in positivity rate seen in week 40, 2020 (65.2%) (Figure 12). In week 30, 2021, there were no positive specimens for influenza A or B; there has only been one avian influenza A(H9N2) case detected for 2021 in week 8 (Figure 13). Influenza Situation Update | 8 Figure 12: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 13: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 9 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 19 July to 1 August 2021, there were 21 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 435 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average (Figure 14). Figure 14: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, influenza-like illness (ILI) activity has decreased in the week ending 1 August 2021. Community ILI activity remains very low for this time of year. The rates of Healthstat consultations for ILI remain below the levels seen at the same time in recent years and at the same time in 2020. The ILI consultation rate in the 0-4 year age group in the week ending 1 August are at a similar level to the historical rate for this time of year (Figure 15). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are currently four influenza cases detected through the surveillance system in 2021. Influenza Situation Update | 10 Figure 15: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 30 of 2021, increases in the number of ILI cases have been seen in Kiribati, Federated States of Micronesia, Marshall Islands and Northern Mariana Islands. The increase seen in Fiji, Solomon Islands, and Vanuatu may be due to the increased number of sites reported for the week. Reduction of ILI cases have been seen in New Caledonia, Palau, and Wallis & Futuna. The reduction seen in Tonga may be due to the decreased number of sites reported for the week. (Figure 16). Influenza Situation Update | 11 * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 16: Reported cases of influenza-like illness in Pacific Island Countries, 26 July to 1 August 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 25 August 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 33 of 2021 are presented in table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 35, 2020 to week 33, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 33, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 35, 2020 to week 33, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (32) 60226 3 Cambodia (30) 2725 0 China (32) 404053 6738 Fiji (4) 222 Japan (31) 4 Lao People's Democratic Republic (33) 2050 146 Malaysia (33) 2073 2 Mongolia (31) 306 0 New Caledonia New Zealand Papua New Guinea Philippines (29) 322 40 Republic of Korea Singapore (32) 1815 1 Viet Nam (30) 497 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 32 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.2%, lower than last week (2.3%), and higher than the same period in 2018-2020 (2.1%, 2.1% and 2.0%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 31 of 2021, there was a slight decrease in ILI activity in Mongolia from the previous report, with four ILI cases per 10,000 population for week 31. This is higher than the lower tolerance limit of zero ILI cases per 10,000 population, yet lower than the upper tolerance limit of 19 per 10,000 population (Figure 3). Figure 3: Proportion of outpatient ILI visitsper 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 33 of 2021, the overall weekly ILI rate was 1.2 ILI cases per 1,000 outpatient visits, which was slightly lower than the previous week (1.6 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n s 2020-2021 Seasonal threshold Week Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 31 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 33 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.4 ILI cases per 1,000 consultations, which was lower than 0.6 ILI cases per 1,000 consultations recorded in the previous week and slightly less than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 6.7 ILI cases per 1,000 consultations, which was lower than 9.2 recorded in the previous week and the lowest ILI rate recorded during the same period from 2017 to current (Figure 7). Influenza Situation Update | 5 Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During week 32 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.0%, lower than the previous week (3.3%), higher than the same week of 2018 and 2020 (2.8% and 2.7%, respectively) and lower than during the same period in 2019 (3.2%) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In week 32 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 964 over 4.5 working days, higher than the previous season in 2020 (Figure 9). Of 151 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%. The last specimen to test positive for influenza was collected in July 2021 and tested positive for influenza B (Figure 10). Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Figure 10: Monthly influenza surveillance for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 7 Lao PDR From 7 to 13 August 2021, the proportion of ILI cases presenting to sentinel sites has slightly decreased compared to the previous week. Since week 18, ILI presentations have been lower compared to the 3-year average (Figure 11). Figure 11: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 32 of 2021, the number of ILI cases reported weekly by sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a peak in positivity rate seen in week 40, 2020 (65.2%) (Figure 12). In week 32, 2021, there were no positive specimens for influenza A or B; there has only been one avian influenza A(H9N2) case detected for 2021 in week 8 (Figure 13). Figure 12: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Figure 13: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 2 August to 15 August 2021, there were 21 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 462 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average (Figure 14). Figure 14: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) Influenza Situation Update | 9 New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, influenza-like illness (ILI) activity has decreased in the week ending 15 August 2021. Community ILI activity remains very low for this time of year. The rates of Healthstat consultations for ILI mirror the same levels seen at the same time in recent years and at the same time in 2020. However, the ILI consultation rate in the 0-4 year age group in the week ending 15 August are at a similar level to the historical rate for this time of year (Figure 15). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are currently five influenza cases detected through the surveillance system in 2021. Figure 15: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020- 2021 (Source: New Zealand Institute of Environmental Science and Research) Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 32 of 2021, increases in the number of ILI cases have been seen in Northern Mariana Islands with a slight increase in Palau. The increase seen in Solomon Islands and Tonga may be due to the increased number of sites reported for the week. A reduction of ILI cases have been seen in Tuvalu. The reduction seen in New Caledonia and Vanuatu may be due to the decreased number of sites reported for the week. (Figure 16). Influenza Situation Update | 10 * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 16: Reported cases of influenza-like illness in Pacific Island Countries, 9 August to 15 August 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 8 September 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 35 of 2021 are presented in Table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 37, 2020 to week 35, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 35, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 37, 2020 to week 35, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (34) 65488 3 Cambodia (32) 3208 0 China (34) 426304 7391 Fiji (4) 222 Japan (33) 4 Lao People's Democratic Republic (35) 2105 146 Malaysia (33) 2073 2 Mongolia (31) 306 0 New Caledonia New Zealand Papua New Guinea Philippines (32) 391 48 Republic of Korea Singapore (34) 1897 1 Viet Nam (30) 497 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 34 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 1.7%, lower than last week (2.0%), lower than the same period in 2018-2019 (2.1%, and 2.0%, respectively), and the same during week 34 of 2020 (1.7%) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 33 of 2021, there was a slight decrease in ILI activity in Mongolia from the previous week, with four ILI cases per 10,000 population as compared to 13 for week 32. This is higher than the lower tolerance limit of one ILI cases per 10,000 population, yet lower than the upper tolerance limit of 20 per 10,000 population for this week (Figure 3). Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 35 of 2021, the overall weekly ILI rate was 0.9 ILI cases per 1,000 outpatient visits, which was slightly lower than the previous week (1.1 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/1 ,0 00 O ut pa tie nt Co ns ul ta tio ns 2020-2021 Seasonal threshold Week Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 33 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 35 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.3 ILI cases per 1,000 consultations, which was lower than 0.8 ILI cases per 1,000 consultations recorded in the previous week and slightly less than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 10.5 ILI cases per 1,000 consultations, which was lower than 6.9 recorded in the previous week and the lowest ILI rate recorded during the same period from 2017 to current (Figure 7). Influenza Situation Update | 5 Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During week 34 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 2.6%, lower than the previous week (2.8%) and lower than the same period in 2018- 2020 (2.7%, 2.9%, and 2.7%, respectively) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In week 34 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1082 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 136 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%. The last specimen to test positive for influenza was collected in July 2021 and tested positive for influenza B (Figure 10). Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Figure 10: Monthly influenza surveillance for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 7 Lao PDR From 14 to 20 August 2021, the proportion of ILI cases presenting to sentinel sites has slightly decreased compared to the previous week. Since week 18, ILI presentations have been lower compared to the 3-year average (Figure 11). Figure 11: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 33 of 2021, the number of ILI cases reported weekly by sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a peak in positivity rate seen in week 40, 2020 (65.2%) (Figure 12). In week 33, 2021, there were no positive specimens for influenza A or B; there has only been one avian influenza A(H9N2) case detected for 2021 in week 8 (Figure 13). Year-Week Figure 12: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Figure 13: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 16 August to 29 August 2021, there were 21 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 483 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average (Figure 14). Figure 14: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) Influenza Situation Update | 9 New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, influenza-like illness (ILI) activity has remained low in the week ending 29 August 2021. Community ILI activity remains very low for this time of year. The rates of Healthstat consultations for ILI mirror the levels seen at the same time in 2020. The ILI consultation rates in all age groups in the week ending 29 August are below the historical rates (Figure 15). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are currently five influenza cases detected through the surveillance system in 2021. Figure 15: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Influenza Situation Update | 10 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 34 of 2021, slight increases were seen in the Commonwealth of the Northern Mariana Islands and Wallis & Futuna. The sharp increase in the number of ILI cases seen in the Federated States of Micronesia as well as in Fiji are most likely attributed to the increased number of sites reporting in week 34 as compared to the previous week. A reduction of ILI cases was notably seen in the Republic of the Marshall Islands (Figure 16). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 16: Reported cases of influenza-like illness in Pacific Island Countries, 23 August to 29 August 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 11 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 22 September 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 35 of 2021 are presented in Table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 37, 2020 to week 35, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 35, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 37, 2020 to week 35, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (34) 65488 3 Cambodia (32) 3208 0 China (34) 426304 7391 Fiji (4) 222 Japan (33) 4 Lao People's Democratic Republic (35) 2105 146 Malaysia (33) 2073 2 Mongolia (31) 306 0 New Caledonia New Zealand Papua New Guinea Philippines (32) 391 48 Republic of Korea Singapore (34) 1897 1 Viet Nam (30) 497 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 36 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 1.8%, higher than last week (1.7%), lower than the same period in 2018-2020 (2.1%, 2.0% and 1.9%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 35 of 2021, there was a slight decrease in ILI activity in Mongolia from the previous week, with 15 ILI cases per 10,000 population as compared to 19 for week 34. This is higher than the lower tolerance limit of four ILI cases per 10,000 population, yet lower than the upper tolerance limit of 21 per 10,000 population for this week (Figure 3). Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 37 of 2021, the overall weekly ILI rate was 1.0 ILI cases per 1,000 outpatient visits, which was the same as the previous week (1.0 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/ 1 ,0 0 0 O u tp at ie n t C o n su lt at io n s 2020-2021 Seasonal threshold Week Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 35 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in most of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 37 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.4 ILI cases per 1,000 consultations, which was lower than 0.5 ILI cases per 1,000 consultations recorded in the previous week and slightly higher than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 14.4 ILI cases per 1,000 consultations, which was higher than 10.9 recorded in the previous week and the same ILI rate recorded during the same period the year prior in 2020. (Figure 7). Influenza Situation Update | 5 Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During week 36 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.1%, higher than the previous week (2.7%) and higher than the same period in 2018-2020 (2.7%, 2.9%, and 3.0%, respectively) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In week 36 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1127 over 5.5 working days, higher than the previous season in 2020 (Figure 9). Of 165 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%. The last specimen to test positive for influenza was collected in July 2021 and tested positive for influenza B (Figure 10). Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Figure 10: Monthly influenza surveillance for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Influenza Situation Update | 7 Lao PDR From 4 to 10 September 2021, the proportion of ILI cases presenting to sentinel sites was 10 cases lower compared to the previous week. Of 22 samples tested for influenza this week, zero (0) cases were positive. Since week 18, ILI presentations have been lower compared to the 3-year average (Figure 11). Figure 11: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 34 of 2021, the number of ILI cases reported weekly by sentinel outpatient sites remained low in Cambodia. The number of cases has remained relatively stable after a peak in positivity rate seen in week 40, 2020 (65.2%) (Figure 12). In week 34, 2021, there were no positive specimens for influenza A or B; there has only been one avian influenza A(H9N2) case detected for 2021 in week 8 (Figure 13). Year-Week Figure 12: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Figure 13: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 30 August to 12 September 2021, there were 26 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 512 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average (Figure 14). Figure 14: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) Influenza Situation Update | 9 New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, influenza-like illness (ILI) activity has remained low in the week ending 10 September 2021. Community ILI activity remains very low for this time of year. The rates of Healthstat consultations for ILI mirror the levels seen at the same time in 2020. The ILI consultation rates in all age groups in the week ending 10 September are below the historical rates (Figure 15). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are currently five influenza cases detected through the surveillance system in 2021 (source). Figure 15: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 36 of 2021, slight increases were seen in the Commonwealth of the Northern Mariana Islands, Palau, the Republic of Marshall Islands and Wallis & Futuna. The increase in the number of ILI cases seen in Kiribati, Solomon Islands and Vanuatu are most likely attributed to the increased number of sites reporting in week 36 as compared to the previous week. A reduction of ILI cases was notably seen in Cook Islands, the Federated States of Micronesia and Fiji (Figure 16). Influenza Situation Update | 10 * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 16: Reported cases of influenza-like illness in Pacific Island Countries, 6 September to 12 September 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 11 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. Arabic, Chinese, English, French, Russian, Spanish
Bi-weekly Influenza Situation Update 6 October 2021 Virological Surveillance Summary The total number of specimens and number of positive specimens reported to FluNet by Western Pacific Region countries and areas between week 1 and week 39 of 2021 are presented in Table 1 below. Influenza A and B are co-circulating, however, the majority of cases reported from week 41, 2020 to week 39, 2021 have been Influenza B (Figure 1). Caution should be taken when interpreting these data as there are reporting delays. Table 1: Cumulative data reported to FluNet from Western Pacific Region, week 1, 2021 to week 39, 2021 Figure 1: Number of specimens positive for influenza by subtype, Western Pacific Region, week 41, 2020 to week 39, 2021 (Source: WHO FLUNET) Country (most recent week of report) Total number of specimens processed Total number of influenza positive specimens Australia (39) 76319 4 Cambodia (34) 3584 0 China (38) 462960 8944 Fiji (4) 421 - Japan (37) - 4 Lao People's Democratic Republic (39) 2221 146 Malaysia (39) 2378 2 Mongolia (39) 306 0 New Caledonia - - New Zealand - - Papua New Guinea - - Philippines (38) 519 67 Republic of Korea (38) 3045 0 Singapore (38) 2066 1 Viet Nam (35) 497 39 Influenza Situation Update | 2 Influenza surveillance summary Influenza surveillance in the WHO Western Pacific Region is based on outpatient and inpatient indicator based surveillance (IBS) systems, as well as event-based surveillance. Case definitions, population groups included and data formats differ among countries. This influenza surveillance summary includes countries and areas where routine IBS is conducted and information is available. The WHO surveillance case definition for influenza-like illness (ILI) is an acute respiratory infection with a measured fever of ≥38oC and cough, with symptom onset within the last 10 days. For SARI, it is an acute respiratory infection (ARI) with a history of fever or measured fever of ≥38oC and cough, with symptom onset within 10 days that requires hospitalization. Sentinel site data should be interpreted with caution since the number of sites reporting may vary between weeks. Countries in the temperate zone of the Northern Hemisphere In countries within the temperate zone of the Northern Hemisphere, ILI and influenza activity continues to be lower than in previous seasons. Outpatient ILI Surveillance China (North) During week 38 of 2021, the percentage of visits for ILI at national sentinel hospitals in Northern China was 2.2%, higher than last week (2.0%), lower than the same period in 2018-2020 (2.1%, 2.2% and 2.2%, respectively) (Figure 2). Figure 2: Percentage of visits for ILI at sentinel hospitals in Northern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 3 Mongolia During week 37 of 2021, there was a slight decrease in ILI activity in Mongolia from the previous week, with 15 ILI cases per 10,000 population as compared to 16 for week 36. This is higher than the lower tolerance limit of four ILI cases per 10,000 population, yet lower than the upper tolerance limit of 25 per 10,000 population for this week (Figure 3). Figure 3: Proportion of outpatient ILI visits per 10,000 people in Mongolia, 2019-2021 (Source: Mongolia National Influenza Center) Republic of Korea In week 39 of 2021, the overall weekly ILI rate was 1.0 ILI cases per 1,000 outpatient visits, which was the same as the previous week (1.0 ILI cases per 1,000 outpatient visits). The ILI consulation rate has remained below the national epidemic threshold (5.8 ILI cases per 1,000 outpatient visits) since week 10 of 2020 (Figure 4). Figure 4: Weekly ILI incidence rate per 1,000 outpatient consultations, Republic of Korea, 2017-2021 (Source: Korean Centres for Disease Control and Prevention) 20-21 Seasonal Threshold IL I/1 ,0 00 O ut pa tie nt Co ns ul ta tio ns 2020-2021 Seasonal threshold Week Influenza Situation Update | 4 Sentinel influenza surveillance Japan In week 37 of 2021, the number of cases reported weekly by sentinel hospital sites remained very low in Japan. The number of cases this year has not been in line with usual trends in which seasonal peaks are seen between weeks 1-9, the trend in 2021 has been consistently low with no peak (Figure 5). Figure 5: Number of influenza cases reported weekly per reporting sentinel hospital site, Japan 2011-2021 (Source: Japan National Institute of Infectious Diseases) Influenza Situation Update | 5 Countries/areas in the tropical zone ILI and influenza activity continued to be lower than previous seasons in some of the countries and areas in the tropical zone. Hong Kong SAR (China) – ILI and hospital Surveillance In week 39 of 2021, the average consultation rate for ILI among sentinel general outpatient clinics was 0.5 ILI cases per 1,000 consultations, which was higher than 0.4 ILI cases per 1,000 consultations recorded in the previous week and slightly higher than the rate of consultation during the same period in 2020 (Figure 6). The average consultation rate for ILI among sentinel private medical practitioners was 25.2 ILI cases per 1,000 consultations, which was higher than 20.3 recorded in the previous week and higher than ILI rate recorded during the same period the year prior in 2020. (Figure 7). Figure 6: ILI consultation rates at sentinel general outpatient clinics, Hong Kong SAR 2019-2021 Figure 7: ILI consultation rates at sentinel private doctors, Hong Kong SAR 2017-2021 (Source: Hong Kong Centre for Health Protection) (Source: Hong Kong Centre for Health Protection) China (South) - ILI Surveillance During week 38 of 2021, the percentage of visits for ILI at national sentinel hospitals in Southern China was 3.8%, higher than the previous week (3.5%) and higher than the same period in 2018-2020 (2.9%, 3.2%, and 3.4%, respectively) (Figure 8). Figure 8: Percentage of visits due to ILI at national sentinel hospitals in Southern China, 2018-2021 (Source: China National Influenza Center) Influenza Situation Update | 6 Singapore – Acute Respiratory Infection (ARI) Surveillance In week 38 of 2021, the average daily number of patients seeking treatment in polyclinics for ARI was 1261 over 5.5 working days, slightly higher than the previous season in 2020 (Figure 9). Of 169 samples tested for influenza in the past 4 weeks, the positivity rate in the community was 0.0%. The last specimen to test positive for influenza was collected in July 2021 and tested positive for influenza B (Figure 10). Figure 9: Average daily polyclinic attendances for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Figure 10: Monthly influenza surveillance for ARI in Singapore, 2020-2021 (Source: Singapore Ministry of Health) Lao PDR From 18 to 24 September 2021, the number of ILI cases presenting to sentinel sites was 60, which was 3 cases lower compared to the previous week. Of 11 samples tested for influenza this week, zero (0) cases were positive. Since week 18, the proportion of ILI presentations at sentinel sites have been lower compared to the 3-year average (Figure 11). Influenza Situation Update | 7 Figure 11: Weekly proportion of ILI presentations at sentinel sites for 2021 compared to previous 3-year average (2018 to 2020) (Source: Lao National Center for Laboratory and Epidemiology) Cambodia In week 38 of 2021, the proportion of ILI presentations was 6.3%, which is higher then the previous week (4.2%) and higher than the same period in 2020 (4.3%). (Figure 12). In week 38, 2021, there were no positive specimens for influenza A or B; there has only been one avian influenza A(H9N2) case detected for 2021 in week 8 (Figure 13). Year-Week Figure 12: Number of ILI cases from seven sentinel sites and influenza positivity rate by week, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Figure 13: Number of influenza positive samples by subtype, 2020-2021, Cambodia (Source: Communicable Disease Control Department, Cambodia Ministry of Health) Influenza Situation Update | 8 Countries in the temperate zone of the southern hemisphere In the temperate zone of the southern hemisphere, influenza activity is reported during the influenza season usually starting in May in Australia and New Zealand. Australia – Laboratory-confirmed influenza From 13 to 26 September 2021, there were 21 laboratory-confirmed influenza notification to the National Notifiable Disease Surveillance System (NNDSS). In the year to date, there have been 534 notifications of laboratory-confirmed influenza to the NNDSS. Number of confirmed cases reported have remained low since April 2020 and are lower than the five-year average (Figure 14). Figure 14: Notifications of laboratory-confirmed influenza by month and week from 2016 to 2021 in Australia (Source: National Notifiable Diseases Surveillance System, Australian Department of Health) New Zealand – Influenza like Illness Overall, based on multiple sources of surveillance information, influenza-like illness (ILI) activity has remained low in the week ending 24 September 2021. Community ILI activity remains very low for this time of year. The rates of Healthstat consultations for ILI are lower than the levels seen at the same time in 2020. The ILI consultation rates in all age groups in the week ending 24 September are below the historical rates (Figure 15). Public Health Units routinely investigate respiratory outbreaks, including laboratory testing of a sample of cases. There are currently five influenza cases detected through the surveillance system in 2021 (source). Figure 15: Weekly rates of general practice ILI consultations per 100,000 people in New Zealand in 2020-2021 (Source: New Zealand Institute of Environmental Science and Research) Influenza Situation Update | 9 Pacific Island Countries and Areas (PICs) - ILI Surveillance In the Pacific Island Countries and Areas, in week 38 of 2021, slight increases were seen in the Federated States of Micronesia and Niue. The increase in the number of ILI cases seen in Cook Islands islikely attributed to the increased number of sites reporting in week 38 as compared to the previous week. A reduction of ILI cases was seen in Commonwealth of the Northern Mariana Islands, Fiji, Kiribati, Palau and Republic of the Marshall Islands. The decrease in Solomon Islands and Vanuatu may be due to the decreased number of sites reported for the week. (Figure 16). * Caution should be taken in interpreting these data as there may be changes in the number of sentinel sites reporting to the Pacific Syndromic Surveillance System. Figure 16: Reported cases of influenza-like illness in Pacific Island Countries, 6 September to 12 September 2021 (Source: Pacific Syndromic Surveillance System Weekly Bulletin) Influenza Situation Update | 10 Global influenza situation updates Virological update Global update Others: • Recommended composition of influenza virus vaccines for use in the 2021 southern hemisphere influenza season Link • Recommended composition of influenza virus vaccines for use in the 2020-2021 northern hemisphere influenza season Link WHO's YouTube Channel: film exploring a number of key aspects of the constant evolution of influenza viruses and associated impacts on public health. 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