Abstract

Regional and global elimination of immunization infections require transboundary cooperation and coordination. In a highly interconnected world, transboundary mobility of populations could promote free-riding in vaccination efforts between populations and result in lower vaccination coverage in each population relative to the global optimum. In the absence of a global body that can impose a universal vaccination strategy, incentives for individual countries to invest in vaccination are influenced by their neighbor’s vaccination coverage and the ability to form voluntary coalitions that reward countries that join by cooperatively increasing vaccination coverage. Here we explore conditions that support self-enforcing coalitions using epidemiological models embedded in a game theoretic framework. We find that by forming coalitions, countries can achieve much higher vaccination coverage at a lower cost than when acting independently. Furthermore, when asymmetric countries form coalitions, realized coverage is regionally more consistent and equitable.