Heterogeneity in the probability of HIV transmission per sexual contact: The case of male-to-female transmission in penile—vaginal intercourse

Authors

  • James A. Wiley,

    1. Survey Research Center and San Francisco Men's Health Study, University of California, Berkeley, California 94720, U.S.A.
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  • Stephen J. Herschkorn,

    1. Survey Research Center and San Francisco Men's Health Study, University of California, Berkeley, California 94720, U.S.A.
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  • Nancy S. Padian

    1. San Francisco Men's Health Study, University of California, Berkeley, and Department of Epidemiology and International Health, University of California, San Francisco General Hospital, Building 90, Ward 95, Room 512, 1001 Potrero Avenue, San Francisco, California 94110, U.S.A.
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Abstract

Recent studies have indicated variation in the infectivity β of HIV among heterosexual couples. We represent this heterogeneity by modelling β as a random variable. Using data on the number of contacts and seroconversion of couples, we fit the model by maximum-likelihood estimation with a beta distribution and a discrete distribution for β. The estimates indicate the heterogeneity is extreme. The limitations of the model and the implications of the results for epidemiologic spread and further research are discussed.

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