Public Health Vaccination Policies for Containing an Anthrax Outbreak

Ron Brookmeyer, Johns Hopkins Bloomberg School of Public Health
Elizabeth Johnson
Robert Bollinger

Abstract

Concern about biological weapons has raised questions about the most effective public health policies to contain an anthrax outbreak1-3. We developed a probability model to predict the impact of different anthrax antibiotic and vaccination policies. An anthrax outbreak can be significantly contained by minimizing the delay until initiation of antibiotic prophylaxis. However, even if mass distribution of antibiotics is completed within 6 days of the initial exposure, then at most about 70% of cases can be prevented. Post-exposure vaccination will not significantly increase that prevention rate if antibiotic adherence is similar or higher than attained in the 2001 U.S outbreak4. However, post-exposure vaccination can be useful either in shortening the duration of a prolonged antibiotic regimen, in the event of an antibiotic resistant strain, or if antibiotic adherence rates are very low. We find that a mass pre-exposure vaccination program for the general population would require very high population coverage rates to significantly increase prevention rates from that achieved with targeted and rapid post-exposure prophylaxis programs.