Inclusion Criteria:

• Aged 18 to 25 years on the day of screening
• Informed consent form signed
• Able to attend all scheduled visits and to comply with all trial procedures
• For a woman, inability to bear a child or negative serum pregnancy test performed at screening (Visit 01)
• Subject entitled to national social security
• Subject registered in the French file of healthy volunteers in clinical trials
• For a woman of child-bearing potential: use of an effective method of contraception (hormonal or barrier method) from at least 3 months prior to screening to 3 months following trial vaccination
• For a woman, inability to bear a child or negative urine pregnancy test.

Exclusion Criteria:

• Previous smallpox vaccination confirmed by vaccination record or typical scar
• Participation in another trial in the 3 months before or during the trial period
• Acute intercurrent or chronic illness during the trial
• Breast-feeding
• Allergy or sensitivity to any known components of vaccinia immune globulin or previous reaction to immunoglobulins or trial vaccine
• Congenital or acquired immunodeficiency or immunosuppressive therapy or any treatment including corticosteroids
• Treatment with antiviral drugs within 1 month before vaccination
• History of organ or bone marrow transplant or skin disorders
• Personal or family history of autoimmune disease or cardiac disease, including cardiac risk factors
• History or current central nervous system disease
• Ongoing acute infectious disease
• Blood or blood-derived products received in the past 6 months
• Any vaccination with a live-attenuated vaccine within the 60 days or other vaccines within 40 days preceding the trial vaccination
• Vaccination planned in the 8 weeks following the trial vaccination
• Planned or foreseeable close contact after vaccination with infants less than 12 months, or with immuno-suppressed persons, pregnant and/or lactating woman, or practice of contact or water sports after vaccination before the crust separates
• Skin wound near the vaccination site
• Apparent lack of personal hygiene
• Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent
• HIV, hepatitis B or hepatitis C seropositivity (screening tests)
• Abnormal lab values for hematological parameters or cardiac enzyme (screening tests)
• Feverish illness (oral temperature >=37.5°C, rectal equivalent temperature >=38.0°C) on the day of vaccination.