Take Rate, Immunogenicity and Safety of Elstree-BN Smallpox Vaccine in Healthy Vaccinia-Naive Subjects

Inclusion Criteria: * Signed informed consent * Free of obvious health problems * Negative HIV test * Negative hepatitis B surface antigen and negative antibody to hepatitis C virus * Hematocrit ≥ 38%; white blood cells between 4.0 and 10.0 / nl with differential blood count without clinical finding; and platelets between 150 and 400 / nl * ALT \< 1.5 times institutional upper limit of normal * Negative urine glucose by dipstick or urinalysis * Adequate renal function defined as a serum creatinine \< 1.5 mg/dL; urine protein \< 100 mg/dL or \< 2+ proteinuria; and a calculated creatinine clearance \> 55 mL/min. * For women, negative pregnancy test at screening and within 24 hours prior to vaccination. * If the volunteer is female and of childbearing potential, she agrees to use acceptable contraception. Exclusion Criteria: * Pregnancy or breast-feeding * Known or suspected history of smallpox vaccination * Typical vaccinia scar * Vaccinia specific antibodies at screening * History of immunodeficiency * Known or suspected impairment of immunologic function * Use of immunosuppressive medication or radiation therapy * Any history of atopic disease * Eczema of any degree or history of eczema * Chronic exfoliative skin disorders/conditions or any acute skin disorders of large magnitude * Any malignancy including leukemia or lymphoma * Presence of any infectious disease or a history or evidence of autoimmune disease * History or clinical manifestation of clinically significant mental illness or haematological, renal, hepatic, pulmonary, central nervous, cardiovascular or gastrointestinal disorders * History of drug or chemical abuse * Administration of inactivated vaccine 14 days prior to vaccination * Any immune modifying therapy within 4 weeks prior to vaccination * Administration of live attenuated vaccines within 60 days prior to vaccination * Receipt of blood products or immunoglobulin in the past 6 months * Subjects with acute febrile illness within one week prior to vaccination or subjects who may be in the incubation period of an infectious disease * Household contacts/sexual contacts with, or occupational exposure to any of the following: 1. Pregnant women 2. Children \<12 months of age 3. People with current or history of atopic dermatitis 4. People with chronic exfoliative skin disorders/conditions or any acute skin disorders 5. People with immunodeficiency disease, malignancies or use of immunosuppressive medications * History of anaphylaxis or severe allergic reaction * Hypersensitivity to egg or chick protein * Known allergies to any component of the vaccine or its diluent * Known allergies to any known component of VIG * Known allergies to cidofovir or probenecid * Abnormalities suggestive of any underlying disease, detected at routine tests prior to study inclusion * Use of any investigational or non-registered drug or vaccine starting 30 days preceding the study vaccine and ending at conclusion visit * History of myocardial infarction, angina, congestive heart failure, cardiomyopathy, stroke or transient ischemic attack, or other heart condition under the care of a doctor. * Three or more of the following risk factors: An immediate family member who has had onset of ischemic heart disease before age 50 years, elevated blood pressure, elevated blood cholesterol, diabetes or nicotine abuse.