Questions & Answers
Smallpox - Vaccine Effectiveness
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  1. How long does a smallpox vaccination last?
    Past experience indicates that the first dose of the vaccine offers protection from smallpox for three to five years, with decreasing immunity thereafter. If a person is vaccinated again later, immunity lasts longer. A report from Europe in the 1970s suggests that people vaccinated 10 or 20 or more years ago have enough immunity to lessen their chance of death if infected. However, these people need another dose of smallpox vaccine to restore their full immunity.

  2. Is there a test to determine if someone is still immune from a past smallpox vaccination?
    There are no reliable blood tests to determine if someone is still immune to smallpox.

  3. If someone already had a smallpox vaccination in the past (when they were younger, or in the 1980's in the military), will they have to get it again?
    If more than 10 years have passed since your last vaccination, you will be revaccinated in accordance with DoD's Policy on Administrative Issues Related to Smallpox Vaccination Program.

  4. Will I have to get another dose of smallpox vaccine 5 or 10 years from now?
    The need for additional smallpox vaccination will be based on the threat assessment at the time. If there is still a perceived threat, then, yes, you may be given another vaccination, depending on your job and location.

  5. Will I be protected against all types of smallpox?
    Smallpox vaccine contains live vaccinia viruses. Once administered, it evokes an immune response that protects against variola virus, the virus that causes smallpox.