Individual versus public priorities in the determination of optimal vaccination policies.

There is a tendency for governments to decide whether or not to offer routine vaccination on the basis of arguments of financial cost, whereas individuals decide whether or not to accept vaccination on the basis of their perception of the risks involved. Furthermore, some vaccines impart, or appear to impart, a degree of indirect protection to nonvaccinated individuals in the community. For both of these reasons, public motives concerning vaccination differ from those of the individual. The quantitative implications of these differences are explored in this paper. It is found that, under a broad range of conditions, rational informed individuals would "choose" a lower vaccine uptake than would the community if it acted as a whole. The result is applied to the pertussis situation in England over the past 30 years and provides a measure of a public's changing perception of the risks associated with that vaccine.