Evolutionary vaccination dynamics under higher-order reinforcement pressure

TL;DR

This study models how higher-order social interactions and peer reinforcement influence vaccination behavior, revealing that moderate reinforcement maximizes coverage while excessive reinforcement hampers uptake, with implications for public health strategies.

Contribution

It introduces a novel behavioral-epidemiological model combining multiplex contact structures and reinforcement learning to analyze vaccination dynamics.

Findings

Higher-order social structures create protective vaccination clusters.

Moderate reinforcement (~0.5) optimizes vaccination coverage.

Excessive reinforcement reduces vaccination uptake and outbreak suppression.

Abstract

Vaccination games in higher-order settings remain underexplored, despite their importance in shaping opinions and collective decisions. Here, we introduce a parsimonious behavioral-epidemiological model to evaluate how peer reinforcement pressure influences vaccination uptake. The framework consists of a two-layer multiplex: an epidemic layer governed by the SIR process on a square lattice, and a behavioral layer represented by a hypergraph of triadic interactions. Individuals update their vaccination strategy via imitation, modulated by a reinforcement parameter $\alpha$ when peer support is present. We find that higher-order structure alone induces clusters of vaccinated individuals that act as protective barriers. Low but nonzero reinforcement ($\alpha \approx 0.5$) maximizes coverage and suppresses outbreaks, while both negligible ($\alpha \approx 0$) and moderate ($\alpha > 0.1$) reinforcement reduce uptake, as excessive confirmation lowers adaptability and enables non-vaccinators to re-emerge. Our work bridges complex contagion theory with evolutionary game dynamics, offering insights into how contact structure and peer reinforcement jointly shape vaccination behavior.