Policies for Biodefense Revisited: The Prioritized Vaccination Process for Smallpox

Abstract

Handling bioierror events that involve contagious agents is a major concern in the war against terror, and is a cause for debate among policymakers about the best response policy. At the core of this debate stands the question which of the post-event policies to adopt: mass vaccination--where maximum vaccination capacity is utilized to uniformly inoculate the entire population, or trace (also called ring or targeted) vaccination--where mass vaccinations capabilities are ttaded off with tracing capabilities to selectively inoculate only contacts (or suspected contacts) of infective individuals. We present a dynamic epidemic-intervention model that expands previous models by capturing some additional key features of the situation and by generalizing some assumptions regarding the probability distributions of inter-temporal parameters. The model comprises a set of difference equations. The model is implemented to analyze alternative response policies. It is shown that a mixture of mass and trace vaccination policies--the prioritized vaccination policy--is more effective that either of the two aforementioned policies.