Influenza at the beginning of the 21st century

Bull World Health Organ 2012;90:247–247A | doi:10.2471/BLT.12.104653 Editorials 247 As if nature had intentionally paved the way, the first influenza pandemic of the 21st century was preceded by two disease outbreaks of global importance: highly pathogenic avian influenza (HPAI) H5N1 virus infection appeared in humans in 1997 and was followed in 2003 by severe acute respiratory syndrome (SARS). In 2004, HPAI re-emerged and spread west from south-eastern Asia until it reached Europe and Africa in 2005. The clinical syndromes caused by these viruses were severe enough to trigger pandemic and epidemic preparedness efforts by the global public health community. Heightened political interest has led to substantial investment in influenza surveillance and response activities, particularly the expansion of laboratory surveillance to nearly all parts of the world. The National Influenza Centres of the Global Influenza Surveillance and Response System (GISRS), which exist in 106 of the 193 Member States of the World Health Organization (WHO),1 diagnose influenza and report influenza activity to the GISRS. This enables WHO to map the circulation of influenza viruses and to select the best viruses for the production of seasonal and pandemic influenza vaccines. The impact of influenza on society has been amply studied in high-income economies, where seasonal influenza vaccination policy seeks to protect high-risk groups from the complica- tions of severe disease. However, how influenza viruses behave in tropical climates and how people living in lower- income countries with complex health problems are affected by influenza need further exploration. Efforts to probe these questions have been made, as shown by Steffen et al. in this issue,2 and studies by researchers like Feikin et al.3 and Homaira et al.,4 also in this issue, have contributed important new data. It is encouraging that more and more influenza research is being carried out in countries that cover a broad geographi- cal and economic spectrum. The polymerase chain reaction (PCR), a laboratory diagnostic method with high sensitivity and specificity, is the technology behind these studies. The technique makes it possible to identify the etiologic agent causing influenza- like illness, including influenza viruses, in an extremely short time. This and other advanced technologies have re- sulted in the development of rapid on- site diagnostic systems that will greatly contribute to the clinical management of severe acute respiratory infections and epidemic control. Two major pharmaceutical interven- tions for influenza control and preven- tion are currently in use: vaccination and antiviral treatment. Neither is perfect. Influenza vaccines, which have been in use a long time, are safe but need to be ad- ministered annually and their immuno- genicity in high-risk groups, such as very young children, the elderly and severely immunocompromised patients, is lower than in the rest of the population.5,6 Anti- viral drugs are in very limited supply and the choices are few, a clear disadvantage if drug resistance develops. Furthermore, their effectiveness when initiated late in severely ill patients has not been clearly established.7 The effectiveness of vaccines and antivirals against influenza B viruses has been less clearly established than their effectiveness against A viruses.8 Studies published recently, including one in this issue by Feng et al.,9 highlight the importance of influenza B virus infection in severe influenza disease.10 Because of the aforementioned limitations and the shortage of resources in some settings, influenza control has to often rely on or be backed up by non-pharmaceutical interventions and syndromic case management of severe acute respiratory infection (SARI). In this issue, Bolton et al.11 and Cohen et al.12 propose potential approaches to influenza control. Improved diagnostic technologies have shown that influenza is a much more important component of SARI than formerly thought, although to different degrees from year to year.13 Integrated pneumonia prevention and treatment interventions are clearly the way forward. The world has just experienced the century’s first influenza pandemic. The two outstanding characteristics of the 2009 A(H1N1) influenza pandemic were its ability to cause major out-of-season epidemics in temperate countries and to cause unusually severe disease and death among the young and in healthy people. It was the first influenza pandemic for which both antiviral drugs and vaccines were deployed and for which national pandemic preparedness plans were put in effect in developed countries and many lower-income countries. Nonethe- less, it is thought that the pandemic has claimed hundreds of thousands of lives in one year. When compared with the death toll during an average influenza year, this figure may seem insignificant, yet the years of life lost in the pandemic were higher, considering that during normal influenza season at least 90% of deaths occur in people over 65 years of age.14 Several years are expected to tran- spire before the 2009 influenza pandem- ic virus acquires the full characteristics of a seasonal influenza virus. In 2010, the global response to the A(H1N1) pan- demic was assessed by the International Health Regulations Review Committee, an external body of experts with a broad mix of scientific expertise and practical experience in public health. In its final report, the Committee recommended that WHO amend its pandemic pre- paredness guidance to include measures for assessing disease severity.15 The challenge ahead is to ensure the resources and momentum needed to continue the important work under way in spite of the current global economic recession. Integrating international ef- forts to reduce pneumonia mortality, increasing global capacity to respond to health emergencies and improving basic health systems can help us overcome the challenge. ■ References Avai lable at : http://www.who. int/bul let in/ volumes/90/4/12-104653 Influenza at the beginning of the 21st century Nahoko Shindoa & Sylvie Brianda a World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland. Correspondence to Nahoko Shindo (e-mail: shindon@who.int). Editorials Bull World Health Organ 2012;90:247–247A | doi:10.2471/BLT.12.104653247A 1. World Health Organization [Internet]. Influenza. Global Influenza Surveillance and Response System (GISRS). Available from: http://www. who.int/influenza/gisrs_laboratory/en/ [accessed 8 March 2012]. 2. Steffen C, Debellut F, Gessner BD, Kasolo FC, Yahaya AA, Ayebazibwe N et al. Improving influenza surveillance in sub-Saharan Africa. Bull World Health Organ 2012;90:301–305. 3. Feikin DR, Ope MO, Aura B, Fuller JA, Gikunju S, Vulule J et al. The population-based burden of influenza-associated hospitalization in rural western Kenya, 2007–2009. Bull World Health Organ 2012;90:256–263. 4. Homaira N, Luby SP, Alamgir ASM, Islam K, Paul R, Abedin J et al. Influenza- associated mortality in 2009 in four sentinel sites in Bangladesh. Bull World Health Organ 2012;90:272–278. 5. Osterholm MT, Kelley NS, Sommer A, Belongia EA. Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. Lancet Infect Dis 2012;12:36–44. doi:10.1016/S1473-3099(11)70295-X PMID:22032844 6. Kunisaki KM, Janoff E. N. Influenza in immunosuppressed populations: a review of infection frequency, morbidity, mortality and vaccine responses. Lancet Infect Dis 2009;9:493–504. doi:10.1016/S1473-3099(09)70175-6 PMID:19628174 7. Hsu J, Santesso N, Mustafa R, Brozek J, Chen YL, Hopkins JP et al. Antivirals for treatment of influenza: a systematic review and meta-analysis of observational studies. Ann Intern Med Epub 2012 27 Feb PMID:22371849 8. Sugaya N, Mitamura K, Yamazaki M, Tamura D, Ichikawa M, Kimura K et al. Lower clinical effectiveness of oseltamivir against influenza B contrasted with influenza A infection in children. Clin Infect Dis 2007;44:197–202. doi:10.1086/509925 PMID:17173216 9. Feng L, Shay DK, Jiang Y, Zhou H, Chen X, Zheng Y et al. Influenza-associated mortality in temperate and subtropical Chinese cities, 2003-2008. Bull World Health Organ 2012;90:279–288. 10. Paddock CD, Liu L, Denison AM, Bartlett JH, Holman RC, Deleon-Carnes M et al. Myocardial injury and bacterial pneumonia contribute to the pathogenesis of fatal influenza B virus infection. J Infect Dis 2012;205:895–905. 11. Bolton K, McCaw JM, Moss R, Morris RS, Wang S, Burma A et al. Likely effectiveness of pharmaceutical and non-pharmaceutical interventions for mitigating influenza virus transmission in Mongolia. Bull World Health Organ 2012;90:264–271. 12. Cohen AL, Hyde TB, Verani J, Watkins M. Integrating pneumonia prevention and treatment interventions with immunization services in resource-poor countries. Bull World Health Organ 2012;90:289–294. 13. Nair H, Brooks WA, Katz M, Roca A, Berkley JA, Madhi SA et al. Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis. Lancet 2011;378:1917–30. doi:10.1016/S0140-6736(11)61051-9 PMID:22078723 14. Viboud C, Miller M, Olson D, Osterholm M, Simonsen L. Preliminary estimates of mortality and years of life lost associated with the 2009 A/ H1N1 pandemic in the US and comparison with past influenza seasons. PLoS Curr 2010;20:RRN1153. 15. Implementation of the International Health Regulations: report of the Review Committee on the functioning of the International Health Regulations (2005) in relation to pandemic (H1N1)2009. Geneva: World Health Organization; 2011. Available from: http://apps.who.int/gb/ebwha/pdf_files/WHA64/A64_10- en.pdf [accessed 8 March 2012]. References