A Study of Dryvax Vaccine Against Smallpox in Previously Unvaccinated Adults

The purpose of this study is to see how many people respond to a smallpox vaccine when a sore forms where the shot was given. The world was declared free of smallpox in 1980. General routine vaccinations for smallpox were stopped in the U.S. in 1971. In 1976, the recommendation for routine vaccination of healthcare workers was also discontinued. The only people who presently receive this vaccine are people who work with vaccinia virus or monkeypox virus. Because the world was considered free of smallpox infections, this vaccine was no longer produced; there is a limited supply available in the United States. Because of the limited amount of Dryvax vaccine (vaccinia virus) against smallpox, this study will look at the ability to dilute the vaccine making more doses available in the event of a smallpox outbreak. The study seeks to characterize a strategy of vaccination against smallpox with various doses of Dryvax, followed by revaccination with the same dose, if required, in volunteers 18-32 years of age with a negative history of smallpox vaccination.