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Homophily and infections: Static and dynamic effects

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  • Bizzarri, Matteo
  • Panebianco, Fabrizio
  • Pin, Paolo

Abstract

We analyze the effect of homophily in the diffusion of a harmful state between two groups of agents that differ in immunization rates. Homophily has a very different impact on the steady state infection level (that is increasing in homophily when homophily is small, and decreasing when high), and on the cumulative number of infections generated by a deviation from the steady state (that, instead, is decreasing in homophily when homophily is small, and increasing when high). If immunization rates are endogenous, homophily has the opposite impact on the infection level of the two groups. However, the sign of the group-level impact is reversed if immunization is motivated by infection risk or peer pressure. If motivations are group-specific, homophily can decrease immunization in both groups.

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  • Bizzarri, Matteo & Panebianco, Fabrizio & Pin, Paolo, 2025. "Homophily and infections: Static and dynamic effects," Games and Economic Behavior, Elsevier, vol. 150(C), pages 235-259.
    • Handle: RePEc:eee:gamebe:v:150:y:2025:i:c:p:235-259
    DOI: 10.1016/j.geb.2024.12.007
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    Cited by:

    1. Thuilliez, Josselin & Touré, Nouhoum, 2024. "Opinions and vaccination during an epidemic," Journal of Mathematical Economics, Elsevier, vol. 111(C).
    2. Josselin Thuilliez & Nouhoum Touré, 2024. "Opinions and vaccination during an epidemic," Post-Print hal-04490900, HAL.
    3. Josselin Thuilliez & Nouhoum Touré, 2024. "Opinions and vaccination during an epidemic," Université Paris1 Panthéon-Sorbonne (Post-Print and Working Papers) hal-04490900, HAL.

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    More about this item

    Keywords

    Homophily; Diffusion; Epidemics; Vaccination; SIS–type model;
    All these keywords.

    JEL classification:

    • D62 - Microeconomics - - Welfare Economics - - - Externalities
    • D85 - Microeconomics - - Information, Knowledge, and Uncertainty - - - Network Formation
    • I12 - Health, Education, and Welfare - - Health - - - Health Behavior

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