The United States recently implemented smallpox vaccination of selected
military personnel in a national program of preparedness against use of smallpox
as a biological weapon. The resumption of smallpox vaccinations raises important
questions regarding implementation and safety.
To describe the US military smallpox vaccination program.
Descriptive study of the vaccination program from its inception on December
13, 2002, through May 28, 2003.
US Department of Defense (DoD) fixed and field medical treatment facilities
on multiple continents and ships at sea.
US service members and DoD civilian workers eligible for smallpox vaccination.
Main Outcome Measures
Numbers of vaccinations and rates of vaccination exemptions, symptoms,
and adverse events. Data were collected via reports to headquarters and rigorous
surveillance for sentinel events.
In 5.5 months, the DoD administered 450 293 smallpox vaccinations
(70.5% primary vaccinees and 29.5% revaccinees). In 2 settings, 0.5% and 3.0%
of vaccine recipients needed short-term sick leave. Most adverse events occurred
at rates below historical rates. One case of encephalitis and 37 cases of
acute myopericarditis developed after vaccination; all cases recovered. Among
19 461 worker-months of clinical contact, there were no cases of transmission
of vaccinia from worker to patient, no cases of eczema vaccinatum or progressive
vaccinia, and no attributed deaths.
Mass smallpox vaccinations can be conducted safely with very low rates
of serious adverse events. Program implementation emphasized human factors:
careful staff training, contraindication screening, recipient education, and
attention to bandaging. Our experience suggests that broad smallpox vaccination
programs may be implemented with fewer serious adverse events than previously