• 1
    World Health Organization. New influenza A (H1N1) virus infections: global surveillance summary, May 2009. Wkly Epidemiol Rec 2009; 84:173179.
  • 2
    Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, Dawood FS, Jain S, Finelli L et al. Emergence of a novel swine-origin influenza A (H1N1) virus in humans. N Engl J Med 2009; 360:26052615.
  • 3
    World Health Organization. Pandemic (H1N1) 2009 - update 108. Available at (Accessed 13 February 2013).
  • 4
    Cheng VC, To KK, Tse H, Hung JF, Yuen KY. Two years after pandemic influenza A/2009/H1N1: what have we learned? Clin Microbiol Rev 2012; 25:223263.
  • 5
    Cox CM, Blanton L, Dhara R, Brammer L, Finelli L. 2009 Pandemic influenza A (H1N1) deaths among children–United States-2010. Clin Infect Dis 2011; 52:S69S74.
  • 6
    Libster R, Bugna J, Coviello S et al. Pediatric hospitalizations associated with 2009 pandemic influenza A (H1N1) in Argentina. N Engl J Med 2010; 362:4555.
  • 7
    Kamigaki T, Oshitani H. Epidemiological characteristics and low case fatality rate of pandemic (H1N1) 2009 in Japan. PLoS Curr 2009; 1:RRN1139.
  • 8
    Moorthy M, Samuel P, Peter JV et al. Estimation of the burden of pandemic (H1N1)2009 in developing countries: experience from a tertiary care center in South India. PLoS ONE 2012; 7:e41507.
  • 9
    Kilbourne ED. Influenza pandemics of the 20th century. Emerg Infect Dis 2006; 12:914.
  • 10
    World Health Organization. Review of the 2010–2011 winter influenza seasons, northern hemisphere. Wkly Epidemiol Rec 2011; 86:222227.
  • 11
    World Health Organization. Review of the 2011 winter influenza season, southern hemisphere. Wkly Epidemiol Rec 2011; 86:488496.
  • 12
    Viasus D, Cordero E, Rodríguez-Baño J et al. Changes in epidemiology, clinical features and severity of influenza A (H1N1) 2009 pneumonia in the first post-pandemic influenza season. Clin Microbiol Infect 2012; 18:E55E62.
  • 13
    Bolotin S, Pebody R, White PJ et al. A new sentinel surveillance system for severe influenza in England shows a shift in age distribution of hospitalised cases in the post-pandemic period. PLoS ONE 2012; 7:e30279.
  • 14
    Chuang JH, Huang AS, Huang WT et al. Nationwide surveillance of influenza during the pandemic (2009-10) and post-pandemic (2010-11) periods in Taiwan. PLoS ONE 2012; 7:e36120.
  • 15
    Simmerman JM, Uyeki TM. The burden of influenza in East and South-East Asia: a review of the English language literature. Influenza Other Respir Viruses 2008; 2:8192.
  • 16
    Oshitani H, Kamigaki T, Suzuki A. Major issues and challenges of influenza pandemic preparedness in developing countries. Emerg Infect Dis 2008; 14:875880.
  • 17
    Yoshida LM, Suzuki M, Yamamoto T et al. Viral pathogens associated with acute respiratory infections in central Vietnamese children. Pediatr Infect Dis J 2010; 29:7577.
  • 18
    Suzuki M, Thiem VD, Yanai H et al. Association of environmental tobacco smoking exposure with an increased risk of hospital admissions for pneumonia in children under 5 years of age in Vietnam. Thorax 2009; 64:484489.
  • 19
    Li D, Saito R, Le MT et al. Genetic analysis of influenza A, H3N2 and A, H1N1 viruses circulating in Vietnam from 2001 to 2006. J Clin Microbiol 2008; 46:399405.
  • 20
    Hien TT, Boni MF, Bryant JE et al. Early pandemic influenza (2009 H1N1) in Ho Chi Minh City, Vietnam: a clinical virological and epidemiological analysis. PLoS Med 2010; 7:e1000277.
  • 21
    Azziz-Baumgartner E, Alamgir AS, Rahman MH et al. Incidence of influenza-like illness and severe acute respiratory infection during three influenza seasons in Bangladesh, 2008-2010. Bull World Health Organ 2012; 90:1219.
  • 22
    Simmerman JM, Chittaganpitch M, Levy J et al. Incidence, seasonality and mortality associated with influenza pneumonia in Thailand: 2005-2008. PLoS ONE 2009; 4:e7776.
  • 23
    Sakkou Z, Stripeli F, Papadopoulos NG et al. Impact of influenza infection on children's hospital admissions during two seasons in Athens, Greece. Vaccine 2011; 29:11671172.
  • 24
    Feikin DR, Ope MO, Aura B et al. The population-based burden of influenza-associated hospitalization in rural western Kenya, 2007-2009. Bull World Health Organ 2012; 90:256A263A.
  • 25
    Brammer L, Blanton L, Epperson S et al. Surveillance for influenza during the 2009 influenza A (H1N1) pandemic-United States, April 2009-March 2010. Clin Infect Dis 2011; 52:S27S35.
  • 26
    Subramony H, Lai FY, Ang LW, Cutter JL, Lim PL, James L. An epidemiological study of 1348 cases of pandemic H1N1 influenza admitted to Singapore Hospitals from July to September 2009. Ann Acad Med Singapore 2010; 39:283288.
  • 27
    Baggett HC, Chittaganpitch M, Thamthitiwat S et al. Incidence and epidemiology of hospitalized influenza cases in rural Thailand during the influenza A (H1N1) pandemic, 2009-2010. PLoS ONE 2012; 7:e48609.
  • 28
    Bishop JF, Murnane MP, Owen R. Australia's winter with the 2009 pandemic influenza A (H1N1) virus. N Engl J Med 2009; 361:25912594.
  • 29
    Muhammad Ismail HI, Tan KK, Lee YL et al. Characteristics of children hospitalized for pandemic (H1N1) 2009, Malaysia. Emerg Infect Dis 2011; 17:708810.
  • 30
    Libster R, Coviello S, Cavalieri ML et al. Pediatric hospitalizations due to influenza in 2010 in Argentina. N Engl J Med 2010; 363:24722473.
  • 31
    Centers for Disease Control and Prevention (CDC). Update: influenza activity–United States, 2010-11 season, and composition of the 2011-12 influenza vaccine. MMWR Morb Mortal Wkly Rep 2011; 60:705712.
  • 32
    Chowell G, Echevarría-Zuno S, Viboud C et al. Characterizing the epidemiology of the 2009 influenza A/H1N1 pandemic in Mexico. PLoS Med 2011; 8:e1000436.
  • 33
    Aguirre E, Papenburg J, Ouakki M et al. Comparison of pandemic and seasonal influenza in the pediatric emergency department. Pediatr Infect Dis J 2011; 30:633639.
  • 34
    Song X, DeBiasi RL, Campos JM, Fagbuyi DB, Jacobs BR, Singh N. Comparison of pandemic and seasonal influenza A infections in pediatric patients: were they different? Influenza Other Respir Viruses 2012; 6:2527.
  • 35
    Rahamat-Langendoen JC, Tutuhatunewa ED, Schölvinck EH et al. Influenza in the immediate post-pandemic era: a comparison with seasonal and pandemic influenza in hospitalized patients. J Clin Virol 2012; 54:135140.
  • 36
    Carcione D, Giele C, Dowse GK et al. Comparison of pandemic (H1N1) 2009 and seasonal influenza, Western Australia, 2009. Emerg Infect Dis 2010; 16:13881395.
  • 37
    Lindblade KA, Arvelo W, Gray J et al. A comparison of the epidemiology and clinical presentation of seasonal influenza A and 2009 pandemic influenza A (H1N1) in Guatemala. PLoS ONE 2010; 5:e15826.
  • 38
    Everitt AR, Clare S, Pertel T et al. IFITM3 restricts the morbidity and mortality associated with influenza. Nature 2012; 484:519523.