PLoS Medicine (Jul 2011)

Risk factors for severe outcomes following 2009 influenza A (H1N1) infection: a global pooled analysis.

  • Maria D Van Kerkhove,
  • Katelijn A H Vandemaele,
  • Vivek Shinde,
  • Giovanna Jaramillo-Gutierrez,
  • Artemis Koukounari,
  • Christl A Donnelly,
  • Luis O Carlino,
  • Rhonda Owen,
  • Beverly Paterson,
  • Louise Pelletier,
  • Julie Vachon,
  • Claudia Gonzalez,
  • Yu Hongjie,
  • Feng Zijian,
  • Shuk Kwan Chuang,
  • Albert Au,
  • Silke Buda,
  • Gerard Krause,
  • Walter Haas,
  • Isabelle Bonmarin,
  • Kiyosu Taniguichi,
  • Kensuke Nakajima,
  • Tokuaki Shobayashi,
  • Yoshihiro Takayama,
  • Tomi Sunagawa,
  • Jean Michel Heraud,
  • Arnaud Orelle,
  • Ethel Palacios,
  • Marianne A B van der Sande,
  • C C H Lieke Wielders,
  • Darren Hunt,
  • Jeffrey Cutter,
  • Vernon J Lee,
  • Juno Thomas,
  • Patricia Santa-Olalla,
  • Maria J Sierra-Moros,
  • Wanna Hanshaoworakul,
  • Kumnuan Ungchusak,
  • Richard Pebody,
  • Seema Jain,
  • Anthony W Mounts,
  • WHO Working Group for Risk Factors for Severe H1N1pdm Infection

DOI
https://doi.org/10.1371/journal.pmed.1001053
Journal volume & issue
Vol. 8, no. 7
p. e1001053

Abstract

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BackgroundSince the start of the 2009 influenza A pandemic (H1N1pdm), the World Health Organization and its member states have gathered information to characterize the clinical severity of H1N1pdm infection and to assist policy makers to determine risk groups for targeted control measures.Methods and findingsData were collected on approximately 70,000 laboratory-confirmed hospitalized H1N1pdm patients, 9,700 patients admitted to intensive care units (ICUs), and 2,500 deaths reported between 1 April 2009 and 1 January 2010 from 19 countries or administrative regions--Argentina, Australia, Canada, Chile, China, France, Germany, Hong Kong SAR, Japan, Madagascar, Mexico, The Netherlands, New Zealand, Singapore, South Africa, Spain, Thailand, the United States, and the United Kingdom--to characterize and compare the distribution of risk factors among H1N1pdm patients at three levels of severity: hospitalizations, ICU admissions, and deaths. The median age of patients increased with severity of disease. The highest per capita risk of hospitalization was among patients ConclusionsOur results demonstrate that risk factors for severe H1N1pdm infection are similar to those for seasonal influenza, with some notable differences, such as younger age groups and obesity, and reinforce the need to identify and protect groups at highest risk of severe outcomes. Please see later in the article for the Editors' Summary.