Epidemic-Behavior Coevolutionary Vaccination Game Dynamics Under Prospect Theory

Many studies assume that individuals are perfectly rational or only update vaccination strategies at the end of each transmission season, without considering differences in individual perceptions and behaviors. This article proposes a novel coevolutionary model that integrates subjective perceptions with social interactions, where individuals update vaccination strategies within the same transmission season. The coevolutionary model effectively controls epidemic spread within a single transmission season and uncovers nonlinear effects of the factors overlooked by the traditional static synchronous update (SSU) model. We examine how individual decisions evolve in response to a changing epidemic environment and employ a two-layer coupled network to study the interplay between information and epidemic transmission. Our results indicate that higher contact strengths reduce the epidemic threshold, indicating that contact strengths promote the spread of the epidemic in the early stages. As the epidemic progresses, however, the coevolutionary feedback mechanism, driven by individuals’ responses to infection risks, encourages vaccination, thereby controlling epidemic transmission. Unlike traditional conclusions, higher vaccination costs do not necessarily lead to a smaller vaccination equilibrium. The reason may be that higher costs enhance individuals’ aversion to infection risks. In addition, our analysis also reveals that changes in vaccine efficacy duration may be ineffective in reducing infection densities in early outbreaks. However, under the impact of coevolution, the vaccination equilibrium decreases with the increase of the short vaccine efficacy duration, while it increases with the long vaccine efficacy duration.