The Impacts of Subsidy Policies on Vaccination Decisions in Contact Networks

TL;DR

This paper models the effects of different subsidy policies on voluntary vaccination decisions within contact networks, demonstrating that partial cost-offset subsidies outperform free subsidies in increasing vaccination coverage and controlling epidemics.

Contribution

It introduces an evolutionary game theory model to compare free and partial-offset subsidy policies for vaccination, identifying the more effective approach for epidemic control.

Findings

Partial-offset subsidies lead to higher vaccination rates.

Free subsidies are less effective in promoting vaccination.

Model shows subsidy type significantly impacts epidemic control.

Abstract

Often, vaccination programs are carried out based on self-interest rather than being mandatory. Owing to the perceptions about risks associated with vaccines and the `herd immunity' effect, it may provide suboptimal vaccination coverage for the population as a whole. In this case, some subsidy policies may be offered by the government to promote vaccination coverage. But, not all subsidy policies are effective in controlling the transmission of infectious diseases. We address the question of which subsidy policy is best, and how to appropriately distribute the limited subsidies to maximize vaccine coverage. To answer these questions, we establish a model based on evolutionary game theory, where individuals try to maximize their personal payoffs when considering the voluntary vaccination mechanism. Our model shows that voluntary vaccination alone is insufficient to control an epidemic. Hence, two subsidy policies are systematically studied: (1) in the free subsidy policy the total amount of subsidies is distributed to some individuals and all the donees may vaccinate at no cost, and (2) in the part-offset subsidy policy each vaccinated person is offset by a certain proportion of the vaccination cost. Simulations suggest that, since the part-offset subsidy policy can encourage more individuals to be vaccinated, the performance of this policy is significantly better than that of the free subsidy policy.