Estimation of the serial interval of influenza

Epidemiology. 2009 May;20(3):344-7. doi: 10.1097/EDE.0b013e31819d1092.


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.

Conclusion: : 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age of Onset
  • Hong Kong / epidemiology
  • Humans
  • Influenza, Human / diagnosis
  • Influenza, Human / epidemiology*
  • Influenza, Human / physiopathology*
  • Influenza, Human / transmission
  • Models, Statistical
  • Public Health
  • Reverse Transcriptase Polymerase Chain Reaction
  • Time Factors