【Molecular Systems and Materials Chemistry】You don’t need to be very altruistic to stop a pandemic: Self-isolating when infected may be a natural survival strategy, and policymakers can harness it.

A research group, consisting of Professor Ryoichi Yamamoto, Assistant Professor John Molina (Department of Chemical Engineering, Kyoto University), Professor Matthew Turner (University of Warwick, UK), and Project Assistant Professor Simon Schnyder (Institute of Industrial Science, The University of Tokyo), has developed a novel theoretical framework to predict how individuals adjust their behavior during infectious disease outbreaks. Using mathematical modeling and game theory, the team analyzed how personal decision-making—such as whether to reduce social contact when infected—translates into collective epidemic outcomes. Traditionally, self-isolation has been viewed as an altruistic act, since infected individuals receive little direct personal benefit. However, the new model incorporates key factors including infection prevalence, outbreak scale, and the expected time to vaccination, enabling a more realistic assessment of behavioral dynamics. The study reveals that even a minimal degree of altruism can make substantial contact reduction a rational choice for infected individuals. When such behavior is widely adopted, it can significantly mitigate or even prevent large-scale outbreaks. These findings underscore the critical role of voluntary behavioral responses in controlling infectious diseases and offer new insights for designing effective public health policies.

This research was published on Feb 27, 2026 in Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Paper Information

Link

Soft Matter Engineering