Influenza monthly update: December 2021

WHO-EM/CSR/489/E December 2021 Epidemiological weeks 48–52, 2021 Influenza monthly update Disclaimer: The representation of material on the maps contained herein does not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or its authority of frontiers or boundaries. Dotted lines on maps represents approximate border lines for which there may not be full agreement. Figure 1. Influenza geographic distribution/circulation, EMR, December 2021 Influenza activity by subtype Figure 2. Number of positive influenza cases by subtyped viruses and percentage of positive cases by week, EMR, December 2021 Circulating influenza viruses by subtype Source of data: FluNet and EMFLU Figure 3. Subtyped influenza viruses, EMR, December 2021 ▪ During December 2021, national influenza centres and influenza laboratories in the Region tested 99.4% of the total enrolled cases. The Region’s influenza positivity reached 15.2% with Oman recording the highest influenza positivity in the Region (32.4%). ▪ Genetic and antigenic testing: Out of the 3146 subtyped specimens, 2188 specimens (69.5%) were influenza A(H3), 236 specimens (7.5%) were influenza A (H1N1) pdm09, 679 specimens (21.6%) were influenza A (not subtyped), 25 specimens (0.8%) were influenza B (lineage not determined), 17 specimens (0.5%) were influenza B (victoria lineage) and one case was influenza B (Yamagata lineage). © World Health Organization 2021. Some rights reserved. This work is available under the Creative Commons Attribution-Non Commercial-Share Alike 3.0 IGO license (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo). ▪ In the northern Africa influenza transmission zone, influenza A(H3) subtype has been detected in both Morocco and Egypt, with couple detected cases of influenza B (lineage not determined) in Egypt. As for Tunisia, there is no influenza activity during December. ▪ In the western Asia influenza transmission zone, influenza A(H3) was the main detected influenza virus in Iraq, Jordan, Lebanon and Syrian Arab Republic. In Oman, Qatar and United Arab Emirates, both influenza A and B types were detected, with the predominant subtype in Oman being A (H1N1) pdm09, while in Qatar and United Arab Emirates the predominant subtype was A(H3). Saudi Arabia detected three un-subtyped influenza A viruses and three influenza B viruses (lineage not determined). Bahrain reported no influenza activity during December. ▪ In the southern Asia transmission zone, influenza A(H3) virus was the main detected subtype in Afghanistan and Pakistan. In Iran, both influenza A and B types have been detected with influenza A(H3) subtype being the predominant influenza virus detected. In December 2021 (weeks 48–52), 15 countries in the Eastern Mediterranean Region (EMR) reported data to FluNet and EMFLU, namely Afghanistan, Bahrain, Egypt, Iran (Islamic Republic of), Iraq, Jordan, Lebanon, Morocco, Oman, Pakistan, Qatar, Saudi Arabia, Syrian Arab Republic, Tunisia and United Arab Emirates. Out of the 20 869 enrolled cases in the Region during this month, 20 737 specimens were tested for influenza, of which only 3146 specimens tested positive. 0 10 20 30 40 50 60 70 80 90 100 0 100 200 300 400 500 600 700 800 W 5 2 W 5 3 W 0 1 W 0 2 W 0 3 W 0 4 W 0 5 W 0 6 W 0 7 W 0 8 W 0 9 W 1 0 W 1 1 W 1 2 W 1 3 W 1 4 W 1 5 W 1 6 W 1 7 W 1 8 W 1 9 W 2 0 W 2 1 W 2 2 W 2 3 W 2 4 W 2 5 W 2 6 W 2 7 W 2 8 W 2 9 W 3 0 W 3 1 W 3 2 W 3 3 W 3 4 W 3 5 W 3 6 W 3 7 W 3 8 W 3 9 W 4 0 W 4 1 W 4 2 W 4 3 W 4 4 W 4 5 W 4 6 W 4 7 W 4 8 W 4 9 W 5 0 W 5 1 W 5 2 2020 2021 % o f p o si ti ve c as e s N u m b e r o f p o si ti ve c as e s Epi week A (H1N1) pdm09 A (H3) A (H5) A (not subtyped) B (lineage not determined) B (Victoria lineage) B (Yamagata lineage) Sum of % of positive cases 7.5% 69.5% 21.6% 0.8% 0.5% A (H1N1) pdm09 A (H3) A (H5) A (not subtyped) B (lineage not determined) B (Victoria lineage) B (Yamagata lineage)