Dynamic epidemiology and the market for vaccinations

The intent of this paper is to raise the question of how and when externalities can arise in the market for vaccinations. Static and dynamic models of such markets are developed and compared. A special case in a continuous-time dynamic framework is examined and is found to be efficient, i.e. there is no externality. This is in contrast to the results from the static formulation, raising doubts about the suitability of a static approach. These results indicate that the question of whether there are externalities in individual immunization decisions is more involved than is generally supposed.