A note on the distribution of the number of vaccinated infected under non-random mixing conditions

A common situation in vaccine efficacy (VE) estimation is dealing with non‐randomly mixing populations, which may subject vaccinated and unvaccinated individuals to a different infection pressure. These conditions may lead to a bias in VE estimates. The derivation of the statistical distribution of...

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Bibliographic Details
Published in:Statistics in medicine 2001-07, Vol.20 (13), p.1983-1986
Main Author: Hernández-Suárez, Carlos M.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Computerized, statistical medical data processing and models in biomedicine
Humans
Medical sciences
Medical statistics
Models, Immunological
Vaccination - standards
Vaccines - immunology
Vaccines - standards
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Summary:A common situation in vaccine efficacy (VE) estimation is dealing with non‐randomly mixing populations, which may subject vaccinated and unvaccinated individuals to a different infection pressure. These conditions may lead to a bias in VE estimates. The derivation of the statistical distribution of the number of vaccinated and infected out of a sample of n infections in a VE trial is essential to develop estimates and their properties. For randomly mixing populations, it has been shown recently that this follows a hypergeometric distribution for ‘all/nothing’ vaccines, whereas it is a non‐central hypergeometric distribution for ‘leaky’ ones. Here it is shown that these distributions still hold under non‐random mixing conditions, provided that mixing preferences and contact rates are independent of vaccination status. These conditions are met when vaccine and placebo are randomized. Copyright © 2001 John Wiley & Sons, Ltd.
ISSN:0277-6715
1097-0258
DOI:10.1002/sim.824