Vaccination and the theory of games

TLDR

Voluntary childhood vaccination policies create a dilemma where, once enough people are immune, the marginal risk of vaccination outweighs infection risk, allowing self‑interest to impede disease eradication. The study aims to use game theory to explain how individuals decide about vaccination. The authors apply a formal game‑theoretic framework to model vaccination decisions and derive insights into human behavior. The analysis shows that higher perceived vaccine risk leads to larger drops in uptake for highly transmissible diseases, and that post‑scare recovery of coverage is difficult even when risk perception falls.

Abstract

Voluntary vaccination policies for childhood diseases present parents with a subtle challenge: if a sufficient proportion of the population is already immune, either naturally or by vaccination, then even the slightest risk associated with vaccination will outweigh the risk from infection. As a result, individual self-interest might preclude complete eradication of a vaccine-preventable disease. We show that a formal game theoretical analysis of this problem leads to new insights that help to explain human decision-making with respect to vaccination. Increases in perceived vaccine risk will tend to induce larger declines in vaccine uptake for pathogens that cause more secondary infections (such as measles and pertussis). After a vaccine scare, even if perceived vaccine risk is greatly reduced, it will be relatively difficult to restore prescare vaccine coverage levels.