Estimation of the serial interval of influenza.
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.
Cowling
Benjamin J
BJ
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
Fang
Vicky J
VJ
Riley
Steven
S
Malik Peiris
J S
JS
Leung
Gabriel M
GM
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