Impacts of Time-Varying Aspiration on Vaccination Behavior and Epidemic Control

Individual aspiration plays a central role in shaping vaccination decisions and epidemic outcomes. Recent studies have shown that higher aspiration toward immunity can increase vaccine uptake and reduce the social efficiency deficit (SED) [1–4]. However, aspiration in reality is rarely constant. People’s motivation to vaccinate can rise during outbreaks when the risk of infection becomes salient, and decline when cases fall or vaccine fatigue develops. To address this limitation, we extend the aspiration-based vaccination model of Khatun et al. [1] within a SEIRS epidemic framework by incorporating time-varying aspiration. Two simple mechanisms are considered: (i) prevalence-driven aspiration, where aspiration increases with the number of infectious cases, and (ii) time-decaying aspiration, where aspiration gradually declines in the absence of strong risk perception. Using mean-field analysis and numerical simulations, we investigate how dynamic aspiration influences epidemic prevalence, vaccination coverage, and the social efficiency deficit (SED) compared to fixed aspiration levels. Our findings reveal that prevalence-driven aspiration can generate rapid increases in vaccination during outbreaks, effectively suppressing infection peaks, while time-decaying aspiration may lead to delayed responses and higher long-term infection burdens. These results highlight the importance of incorporating dynamic behavioral motivation into vaccination game models and suggest that public health strategies could benefit from actively sustaining aspiration levels over time.

References :

1. Khatun, K., Khan, M. M. U. R., & Tanimoto, J. (2025). Aspiration can decline epidemic disease. Alexandria Eng. J., 112, 151–160. https://www.sciencedirect.com/science/article/pii/S111001682401250X

2. Lyu, Z., Su, Y., & Zhuo, X. (2024). Vaccination games and imitation dynamics with age structure. Chaos Solitons Fractals, 183, 114929. https://doi.org/10.1016/j.chaos.2024.114929

3. Kulsum, U., Alam, M., & Kamrujjaman, M. (2024). Early vs. delayed vaccination under imitation and aspiration dynamics. Chaos Solitons Fractals, 178, 114364. https://doi.org/10.1016/j.chaos.2023.114364

4. Schimit, P. H. T. (2025). Vaccination as a Game: Behavioural Dynamics, Network Effects, and Policy Implications. Mathematics, 13(14), 2242. https://www.mdpi.com/2227-7390/13/14/2242