<qa>  How many healthy adults will volunteer for this study?The purpose of this study is to determine the safety and effect of diluting smallpox vaccine, making a larger number of doses in case smallpox is released into the environment. A total of up to 927 healthy adults between the ages of 32 and 70 years who were already vaccinated against smallpox but not since 1989 will volunteer for this study for up to 34 weeks and receive different strengths of vaccine. Some subjects may participate for longer if they choose to be revaccinated because the first vaccination does not take. The vaccine will be given by making small cuts in the skin and putting the vaccine into these cuts. After the screening visit, volunteers will be followed through study visits and follow up phone calls. Blood will be collected during some study visits to look at the immune system body system that fights infection response. 