title: Transmissibility of seasonal and pandemic influenza in a cohort of households in Hong Kong in 2009.
abstract: BACKGROUND
  The household secondary attack proportion (SAP) is commonly used to measure the transmissibility of an infectious disease.
  
  
  METHODS
  We analyzed the final outbreak size distributions of pandemic A(H1N1), seasonal A(H1N1), and A(H3N2) infections identified in paired sera collected from members of 117 Hong Kong households in April and in August-October 2009.
  
  
  RESULTS
  The estimated community probability of infection overall was higher for children than adults; the probability was similar for pandemic A(H1N1) and seasonal A(H3N2) influenza. The household SAP for pandemic A(H1N1) was higher in children than in adults, whereas for seasonal A(H3N2), it was similar in children and adults. The estimated SAPs were similar for seasonal A(H3N2) and pandemic A(H1N1) after excluding persons with higher baseline antibody titers from analysis.
  
  
  CONCLUSIONS
  Pandemic and seasonal influenza A viruses had similar age-specific transmissibility in a cohort of initially uninfected households, after adjustment for baseline immunity.
authors: School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
authors: Brendan
authors: B
authors: Klick
authors: Hiroshi
authors: H
authors: Nishiura
authors: Sophia
authors: S
authors: Ng
authors: Vicky J
authors: VJ
authors: Fang
authors: Gabriel M
authors: GM
authors: Leung
authors: J S Malik
authors: JS
authors: Peiris
authors: Benjamin J
authors: BJ
authors: Cowling
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005191:Family Characteristics; D005260:Female; D006723:Hong Kong; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity; D053122:Influenza A Virus, H3N2 Subtype / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000706:statistics & numerical data*; D012621:Seasons; D055815:Young Adult