Keywords
Pandemic
A/(H1N1)pdm09
Abstract
In June 2009 the World Health Organization (WHO) issued a pandemic alert concerning the spread of an influenza A (H1N1) virus showing distinctive genetic characteristics vis-à-vis both seasonal influenza strains and vaccine strains. The most relevant mutation occurred in the hemagglutinin (HA). Mathematical models were developed to calculate the virusâs transmissibility and the results indicate a significant overlap with the transmissibility of previous pandemic strains and seasonal strains. The remarkable feature of A/(H1N1)pdm09, compared with seasonal strains, is the high related fatality rate and its higher incidence among younger people. Data provided by the WHO on the number of deaths caused by A/(H1N1)pdm09 only include laboratory-confirmed cases. Some authors suggest that these data underestimate the magnitude of the event because laboratory confirmation is not obtained in all cases. It is important to bear in mind that the A/(H1N1)pdm09 virus is still circulating in the population, making it essential to keep its epidemiological and virological surveillance in place.
References
Taubenberger JK, Reid AH, Lourens RM, Wang R, Jin G, Fanning TG. Characterization of the 1918 influenza virus polymerase genes. Nature 2005;437(7060):889-893. Available from: http://www.nature.com/doifinder/10.1038/nature04230 doi: 10.1038/nature04230. [Google Scholar]
Rambaut A, Pybus OG, Nelson MI, Viboud C, Taubenberger JK, Holmes EC. The genomic and epidemiological dynamics of human influenza A virus. Nature 2008 Apr;453(7195):615-619. Available from: http://europepmc.org/abstract/MED/18418375 PubMed PMID: 18418375. doi: 10.1038/nature06945. [Google Scholar]
Smith DJ, Lapedes AS, de Jong JC, Bestebroer TM, Rimmelzwaan GF, Osterhaus ADME, et al. Mapping the antigenic and genetic evolution of influenza virus.. Science 2004 Jun;305(5682):371-376. Available from: http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=15218094 PubMed PMID: 15218094. doi: 10.1126/science.1097211. [Google Scholar]
Taubenberger JK, Morens DM. 1918 influenza: the mother of all pandemics. Emerg Infect Dis 2006;12(1):15-22. Available from: http://wwwnc.cdc.gov/eid/article/12/1/05-0979_article.htm doi: 10.3201/eid1209.05-0979. [Google Scholar]
Smith GJD, Vijaykrishna D, Bahl J, Lycett SJ, Worobey M, Pybus OG, et al. Origins and evolutionary genomics of the 2009 swine-origin H1N1 influenza A epidemic. Nature 2009 Jun;459(7250):1122-1125. Available from: https://www.nlm.nih.gov/medlineplus/flu.html PubMed PMID: 19516283. doi: 10.1038/nature08182. [Google Scholar]
Gatherer D. The 2009 H1N1 influenza outbreak in its historical con- text. J Clin Virol Off Publ Pan Am Soc Clin Virol 2009;45(3):174-8. Available from: http://linkinghub.elsevier.com/retrieve/pii/S1386653209002534 doi: 10.1016/j.jcv.2009.06.004. [Google Scholar]
WHO. H1N1 in post-pandemic period [Internet]. WHO. Available at: http://www.who.int/mediacentre/news/statements/2010/ h1n1_vpc_20100810/en/ [accessed 09.02.2016].
WHO. FluNet. WHO. Available at: http://www.who.int/influ- enza/gisrs_laboratory/flunet/en/ [accessed 09.02.2016]
Khandaker G, Dierig A, Rashid H, King C, Heron L, Booy R. Systematic review of clinical and epidemiological features of the pandemic influenza A (H1N1) 2009. Influenza Other Respir Vi- ruses 2011;5(3):148-56. Available from: http://doi.wiley.com/10.1111/j.1750-2659.2011.00199.x doi: 10.1111/j.1750-2659.2011.00199.x. [Google Scholar]
Simonsen L, Spreeuwenberg P, Lustig R, Taylor RJ, Fleming DM, Kroneman M, Van Kerkhove MD, Mounts AW, Paget WJ, , Teams GC. Global mortality estimates for the 2009 influenza pandemic from the GLaMOR project: a mod- eling study. PLoS Med 2013;10. PubMed PMID: 1001558. [Google Scholar]
Wong JY, Kelly H, Ip DKM, Wu JT, Leung GM, Cowling BJ. Case fatality risk of influenza A (H1N1pdm09): a systematic re- view. Epidemiol Camb Mass 2013;24(6):830-41. Available from: http://content.wkhealth.com/linkback/openurl?sid=WKPTLP:landingpage&an=00001648-201311000-00006 doi: 10.1097/EDE.0b013e3182a67448. [Google Scholar]
Wong JY, Kelly H, C-mm C, Shiu EY, Wu P, Ni MY, et al. Hospitalization fatality risk of influenza A(H1N1)pdm09: a systematic review and meta-analysis. Am J Epidemiol 2015;182(4):294-301. Available from: https://www.nlm.nih.gov/medlineplus/flu.html PubMed PMID: 26188191. doi: 10.1093/aje/kwv054. [Google Scholar]
Rizzo C, Bella A, Declich S, Rota MC, , Group PIW. Epidemiological surveillance of flu pandemic due to A/H1N1v virus during 2009-2010 flu season. Rapporti ISTISAN 2010;46:1-48. [Google Scholar]
Ministero della Salute. Prevenzione e controllo dell’influenza: raccomandazioni per la stagione 2015-2016. Circolare minis- teriale del 03/09/2015. Available at: http://www.salute.gov.it/ portale/news/p3_2_1_1_1.jsp?lingua=italiano&menu=notizie &p=dalministero&id=2218 [accessed 12/02/2016]
Centers for Disease Control and Prevention (CDC . Prelimi- nary assessment of the effectiveness of the 2003-04 inactivated influenza vaccine – Colorado, December 2003. MMWR Morb Mortal Wkly Rep 2004;53:8-11. [Google Scholar]
BaldoV,BaldovinT,FloreaniA,FragapaneE,TrivelloR, , Group, i.M. (Fam-) . Response of influenza vaccines against heterovariant influenza virus strains in adults with chronic dis- eases. J Clin Immunol 2007;27(5):542-7. Available from: http://link.springer.com/10.1007/s10875-007-9100-4 doi: 10.1007/s10875-007-9100-4. [Google Scholar]
Liu Y, Childs RA, Matrosovich T, Wharton S, Palma AS, Chai W, et al. Altered receptor specificity and cell tropism of D222G hemagglutinin mutants isolated from fatal cases of pan- demic A(H1N1) 2009 influenza virus. J Virol 2010;84(22):12069-74. Available from: http://jvi.asm.org/cgi/doi/10.1128/JVI.01639-10 doi: 10.1128/JVI.01639-10. [Google Scholar]
GokaEA,VallelyPJ,MuttonKJ,KlapperPE . Mutationsasso- ciated with severity of the pandemic influenza A(H1N1)pdm09 in humans: a systematic review and meta-analysis of epidemio- logical evidence. Arch Virol 2014;159(12):3167-83. Available from: http://link.springer.com/10.1007/s00705-014-2179-z doi: 10.1007/s00705-014-2179-z. [Google Scholar]
Halder N, Kelso JK, Milne GJ. Analysis of the effectiveness of interventions used during the 2009 A/H1N1 influenza pandem- ic. BMC Public Health 2010;10(1):168. Available from: http://www.biomedcentral.com/1471-2458/10/168 doi: 10.1186/1471-2458-10-168. [Google Scholar]