Dose Study of ACAM2000 Smallpox Vaccine in Previously Vaccinated Adults

- have a history of previous smallpox vaccination greater than 10 years previous to the date of screening and presence of a vaccination scar.

- females must not be pregnant, lactating and must agree to use an effective form of birth control for the 30 days following vaccination or unable to bear children.

- agree to be available for the entire study and agree to comply with all requirements.

- children 1 year of age or younger in the household or be in close contact

- smallpox vaccination within ten years

- known or suspected Human immunodeficient virus (HIV) infection, primary immunodeficiency disorder, leukemia, lymphoma, or current radiation treatment or use of immunosuppressive or anti-neoplastic drugs or have a household member or intimate contact with the conditions listed above.

- renal disease

- current or past history of eczema or a household member or direct contact who has eczema.

- known allergy or past allergic reactions to latex gloves or to antibiotics which include neomycin, streptomycin, chlortetracycline, and polymyxin B

- known allergy or past allergic reaction to blood products.

- known allergy to cidofovir or sulfa-containing drugs.

- history of allergic phenomena following smallpox vaccination in the past, including urticaria, erythema multiforme, or Stevens-Johnson syndrome.

- transfusion of blood or treatment with any blood product.

- current or history of drug or alcohol abuse

- innoculation with any other live vaccine or participating in another drug or vaccine trial within 30 days of enrollment.