Influence of social peers on vaccine hesitancy under imperfect vaccination

Understanding human responses to epidemic outbreaks—particularly to control measures such as vaccination—is essential for accurately modeling the complex interplay between epidemics and human behavior. Through the framework of evolutionary vaccination games, we explore how individuals' opinions influence vaccine uptake attitudes under imperfect vaccination and, in turn, how this affects to the spread of an epidemic. In our model, individuals update their vaccination strategies by comparing their payoff with one of their neighbors. Individuals payoffs have two contributions regulated by the conformity parameter α. When α→0, the payoff is based on a classical assessment of relative vaccine-to-disease costs Cr, whereas as α→1, individuals have their payoffs influenced by the assortativeness of peers' opinions on the vaccine. The epidemic stage is described by the susceptible-infected-recovery (SIR) model. Extensive simulations have shown that on homogeneous systems, a small region in the parameter space (α,Cr) emerges where the vaccination dilemma can be totally overcome. However, it is also found that social influence tends to promote vaccine hesitancy except for small Cr. Abrupt phase transitions are observed leading the system from high vaccination coverage to full vaccine hesitancy. On heterogeneous networks, the vaccination dilemma has not only been overcome to some extent, but has also demonstrated bi-stability in specific regions. Our results demonstrate the significant impact of social influence on vaccination.