@article{3109703,
    title = "Estimating age-specific cumulative incidence for the 2009 influenza pandemic: A meta-analysis of A(H1N1)pdm09 serological studies from 19 countries",
    author = "Van Kerkhove, M.D. and Hirve, S. and Koukounari, A. and Mounts, A.W. and Allwinn, R. and Bandaranayake and Bella and Bone, A. and Carrat, F. and Chadha, M.S. and Chen, M. and Chi, C.-Y. and Cox and Cretikos, M. and Crowcroft, N. and Cutter, J. and Donnelly, C.A. and de Lamballerie, X. and Dellagi and Doukas, G. and Dudareva-Vizule, S. and Ferguson, N.M. and Fry, A.M. and Gilbert, G.L. and Haas, W. and Hardelid, P. and Horby, P. and Huang, Q.S. and Hungnes, O. and Ikonen, N. and Iwatsuki-Horimoto, K. and Julkunen, I. and Katz, J. and Kawaoka, Y. and Lalvani, A. and Levy-Bruhl, D. and Maltezou, H.C. and McVernon, J. and Miller, M. and Mishra, A.C. and Moghadami, M. and Pawar, S.D. and Reed, C. and Riley, S. and Rizzo, C. and Rosella, L. and Ross, T.M. and Shu, Y. and Skowronski, D.M. and Sridhar, S. and Steens, A. and Tandale, B.V. and Theodoridou, M. and van Boven, M. and Waalen, K. and Wang, J.-R. and Wu, J.T. and Xu, C. and Zimmer, S.",
    journal = "Influenza and Other Respiratory Viruses",
    year = "2013",
    volume = "7",
    number = "5",
    pages = "872-886",
    publisher = "Wiley-Blackwell Publishing Ltd",
    issn = "1750-2640, 1750-2659",
    doi = "10.1111/irv.12074",
    keywords = "cross reacting antibody, 2009 H1N1 influenza;  hemagglutination inhibition;  human;  incidence;  Influenza virus A H1N1;  meta analysis;  nonhuman;  prevalence;  priority journal;  review;  serology;  virus strain, A(H1N1)pdm09;  cross-reactive antibodies;  cumulative incidence;  H1N1pdm;  seroprevalence, Age Factors;  Antibodies, Viral;  Humans;  Influenza A Virus, H1N1 Subtype;  Influenza, Human;  Pandemics;  Seroepidemiologic Studies;  United States",
    abstract = "Background: The global impact of the 2009 influenza A(H1N1) pandemic (H1N1pdm) is not well understood. Objectives: We estimate overall and age-specific prevalence of cross-reactive antibodies to H1N1pdm virus and rates of H1N1pdm infection during the first year of the pandemic using data from published and unpublished H1N1pdm seroepidemiological studies. Methods: Primary aggregate H1N1pdm serologic data from each study were stratified in standardized age groups and evaluated based on when sera were collected in relation to national or subnational peak H1N1pdm activity. Seropositivity was assessed using well-described and standardized hemagglutination inhibition (HI titers ≥32 or ≥40) and microneutralization (MN ≥ 40) laboratory assays. The prevalence of cross-reactive antibodies to the H1N1pdm virus was estimated for studies using sera collected prior to the start of the pandemic (between 2004 and April 2009); H1N1pdm cumulative incidence was estimated for studies in which collected both pre- and post-pandemic sera; and H1N1pdm seropositivity was calculated from studies with post-pandemic sera only (collected between December 2009-June 2010). Results: Data from 27 published/unpublished studies from 19 countries/administrative regions - Australia, Canada, China, Finland, France, Germany, Hong Kong SAR, India, Iran, Italy, Japan, Netherlands, New Zealand, Norway, Reunion Island, Singapore, United Kingdom, United States, and Vietnam - were eligible for inclusion. The overall age-standardized pre-pandemic prevalence of cross-reactive antibodies was 5% (95%CI 3-7%) and varied significantly by age with the highest rates among persons ≥65 years old (14% 95%CI 8-24%). Overall age-standardized H1N1pdm cumulative incidence was 24% (95%CI 20-27%) and varied significantly by age with the highest in children 5-19 (47% 95%CI 39-55%) and 0-4 years old (36% 95%CI 30-43%). Conclusions: Our results offer unique insight into the global impact of the H1N1 pandemic and highlight the need for standardization of seroepidemiological studies and for their inclusion in pre-pandemic preparedness plans. Our results taken together with recent global pandemic respiratory-associated mortality estimates suggest that the case fatality ratio of the pandemic virus was approximately 0·02%. © 2013 John Wiley & Sons Ltd."
}