Episodic outbreaks bias estimates of age-specific force of infection: A corrected method using measles as an example

M. J. Ferrari, A. Djibo, R. F. Grais, B. T. Grenfell, O. N. Bjørnstad

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19 Scopus citations

Abstract

Understanding age-specific differences in infection rates can be important in predicting the magnitude of and mortality in outbreaks and targeting age groups for vaccination programmes. Standard methods to estimate age-specific rates assume that the age-specific force of infection is constant in time. However, this assumption may easily be violated in the face of a highly variable outbreak history, as recently observed for acute immunizing infections like measles, in strongly seasonal settings. Here we investigate the biases that result from ignoring such fluctuations in incidence and present a correction based on the epidemic history. We apply the method to data from a measles outbreak in Niamey, Niger and show that, despite a bimodal age distribution of cases, the estimated age-specific force of infection is unimodal and concentrated in young children (<5 years) consistent with previous analyses of age-specific rates in the region.

Original languageEnglish (US)
Pages (from-to)108-116
Number of pages9
JournalEpidemiology and Infection
Volume138
Issue number1
DOIs
Publication statusPublished - Jan 1 2010

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All Science Journal Classification (ASJC) codes

  • Epidemiology
  • Infectious Diseases

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