title: Estimation of the serial interval of influenza.
abstract: BACKGROUND
  : Estimates of the clinical-onset serial interval of human influenza infection (time between onset of symptoms in an index case and a secondary case) are used to inform public health policy and to construct mathematical models of influenza transmission. We estimate the serial interval of laboratory-confirmed influenza transmission in households.
  
  
  METHODS
  : Index cases were recruited after reporting to a primary healthcare center with symptoms. Members of their households were followed-up with repeated home visits.
  
  
  RESULTS
  : Assuming a Weibull model and accounting for selection bias inherent in our field study design, we used symptom-onset times from 14 pairs of infector/infectee to estimate a mean serial interval of 3.6 days (95% confidence interval = 2.9-4.3 days), with standard deviation 1.6 days.
  
  
  CONCLUSIONS
  : The household serial interval of influenza may be longer than previously estimated. Studies of the complete serial interval, based on transmission in all community contexts, are a priority.
authors.affiliation: Department of Community Medicine and School of Public Health and bMicrobiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China. bcowling@hku.hk
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cowling
authors.forename: Vicky J
authors.initials: VJ
authors.lastname: Fang
authors.forename: Steven
authors.initials: S
authors.lastname: Riley
authors.forename: J S
authors.initials: JS
authors.lastname: Malik Peiris
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
mesh_terms: D017668:Age of Onset; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology* / Q000635:transmission; D015233:Models, Statistical; D011634:Public Health; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors