title: Attack rates assessment of the 2009 pandemic H1N1 influenza A in children and their contacts: a systematic review and meta-analysis.
abstract: BACKGROUND
  The recent H1N1 influenza A pandemic was marked by multiple reports of illness and hospitalization in children, suggesting that children may have played a major role in the propagation of the virus. A comprehensive detailed analysis of the attack rates among children as compared with their contacts in various settings is of great importance for understanding their unique role in influenza pandemics.
  
  
  RESULTS
  We searched MEDLINE (PubMed) and Embase for published studies reporting outbreak investigations with direct measurements of attack rates of the 2009 pandemic H1N1 influenza A among children, and quantified how these compare with those of their contacts. We identified 50 articles suitable for review, which reported school, household, travel and social events. The selected reports and our meta-analysis indicated that children had significantly higher attack rates as compared to adults, and that this phenomenon was observed for both virologically confirmed and clinical cases, in various settings and locations around the world. The review also provided insight into some characteristics of transmission between children and their contacts in the various settings.
  
  
  CONCLUSIONS
  The consistently higher attack rates of the 2009 pandemic H1N1 influenza A among children, as compared to adults, as well as the magnitude of the difference is important for understanding the contribution of children to disease burden, for implementation of mitigation strategies directed towards children, as well as more precise mathematical modeling and simulation of future influenza pandemics.
authors.affiliation: Department of Family and Community Medicine, New York Medical College, Valhalla, New York, United States of America. af1200@nyu.edu
authors.forename: Aharona
authors.initials: A
authors.lastname: Glatman-Freedman
authors.forename: Ian
authors.initials: I
authors.lastname: Portelli
authors.forename: Susan K
authors.initials: SK
authors.lastname: Jacobs
authors.forename: Justin I
authors.initials: JI
authors.lastname: Mathew
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Slutzman
authors.forename: Lewis R
authors.initials: LR
authors.lastname: Goldfrank
authors.forename: Silas W
authors.initials: SW
authors.lastname: Smith
mesh_terms: D002648:Child; D016358:Contact Tracing / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000502:physiology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission*; D058873:Pandemics / Q000706:statistics & numerical data*