Decoding the behavioural dynamics of vaccination: how pre-emptive and post-recovery vaccinations shape epidemic outcomes

This study presents a coupled behavioural–epidemiological framework that integrates an extended susceptible–infected–recovered–susceptible model with evolutionary game theory to analyse timing-based vaccination strategies, specifically pre-infection and post-recovery vaccination. Key findings show that pre-infection vaccination is crucial for immediate transmission control while post-recovery vaccination helps maintain long-term population immunity. The model identifies nine equilibria based on varying adherence levels to both vaccination strategies. Results highlight that vaccination reduces infection levels and emphasize the need to address perceived infection severity among susceptible individuals to limit disease spread. Post-recovery vaccination significantly benefits long-term immunity but has a smaller immediate effect on transmission. The adherence rate (y) to post-recovery is strongly driven by vaccine efficacy, showing less sensitivity to cost. In contrast, pre-infection vaccination adherence rate (x) responds significantly to both efficacy and cost, indicating a dual dependence. The analysis reveals that lower vaccination costs and higher vaccine efficacy lead to a significant reduction in infection rates and increased vaccination coverage, highlighting the importance of strategic vaccination policies for controlling epidemic outbreaks. This timing-based vaccination decision model offers new insights into the complex dynamics of epidemic management and vaccine deployment strategies, informing policy design to encourage timely vaccination.