Vaccination games of boundedly rational parents toward new childhood immunization

Infectious diseases harm societies through disease-induced morbidity, mortality, loss of productivity, and inequality. Thus, controlling and preventing them is critical for public health and societal well-being. However, societies can hinder efforts to control the spread of diseases by failing to adhere to public health recommendations, such as through vaccine hesitancy. Various disease-transmission models have been utilized to help policymakers respond to (re)emerging outbreaks. The usefulness of such models in assessing the effectiveness of public health policies is significantly dependent on human behavior. This paper introduces a new model of parental behavior toward a new childhood immunization. The model incorporates societal features, social norms, and bounded rationality. We integrate this model with the dynamics of childhood disease, as depicted by a standard susceptible-infected-recovered model, to offer a detailed perspective on vaccine acceptance dynamics. We found that the behavioral model provides a new population game theory's replicator dynamical equation with an entropy-like term. Interestingly, societal norms and bounded rationality play a crucial role in shaping vaccine uptake through a novel function, which we term the critical societal vaccine cost. The results suggest that reduced vaccine costs below the critical societal vaccine cost and higher initial acceptance rates increase the probability of disease elimination. A gradual increase in vaccination costs, as an adaptive dynamic policy for disease eradication, is also possible. In particular, strong social norms and low levels of bounded rationality positively contribute to disease eradication even when the basic reproduction number of the disease in that society is large.