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

Estimation of the serial interval of influenza

Benjamin J Cowling  1 , Vicky J Fang, Steven Riley, J S Malik Peiris, Gabriel M Leung
Affiliations

Estimation of the serial interval of influenza

Benjamin J Cowling et al. Epidemiology. 2009 May.

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.

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.

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Figures

Figure 1
Figure 1
Estimated serial interval of influenza (cumulative distributions) using Weibull (solid), gamma (dashed), and lognormal (dot-dashed) parametric models compared with a nonparametric estimate (dotted).
Figure 2
Figure 2
Estimated serial interval of influenza (density function) assuming a Weibull distribution (black line) and the associated uncertainty (gray lines) from 100 parametric bootstrap resamples.
See this image and copyright information in PMC

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