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Smallpox Vaccination Program - Policy

Questions and answers about the DOD Smallpox Vaccination Program, to cover policy and management questions, and military discipline.


Why get vaccinated


Authorities are concerned that terrorists or governments hostile to the United States may have some of the variola virus that causes smallpox disease. If so, they could use it as a biological weapon in bombs or sprays or by other methods. People exposed to variola virus, or those at risk of being exposed, can be protected by vaccinia (smallpox) vaccine.

Smallpox can be prevented through the use of the smallpox vaccine. The World Health Organization (WHO) used smallpox vaccine to eradicate natural smallpox from the planet. About 95% of people are protected within 10 days of getting a single smallpox vaccination.

From 1983 through 2002, most service members did not get vaccinated against smallpox. Those vaccinated before 1983 do not have much immunity left from vaccine given years ago. Until the late 1970s, many billions of people around the globe received smallpox vaccine. Smallpox vaccine is still used routinely to protect a small number of people who work in labs with the smallpox vaccine virus (vaccinia) or similar viruses. Between December 2002 and May 2014, more than 2.4 million service members received smallpox vaccinations.

There is no proven treatment for the smallpox disease, but research to evaluate new antiviral medications is ongoing. Patients infected with smallpox can benefit from supportive therapy (e.g., intravenous fluids, medicine to control fever or pain) and antibiotics for any secondary bacterial infections that occur from all the skin problems smallpox causes.


What if somebody has already been vaccinated years ago


Research indicates that the first dose of smallpox vaccine offers an increased level of protection from smallpox for 3 years. Immunity decreases thereafter. Substantial, but waning immunity persists for 7-10 years. Subsequent vaccinations increase and extend protection. After 3 doses substantial protection persists for >30   years.

In that European study, about 30% of unvaccinated people infected with smallpox died. About 1.4% of people vaccinated up to 10 years earlier died. Among people vaccinated 11 to 20 years earlier, 7% died. Among people vaccinated 21 or more years earlier, 11% died. These data show that immunity falls off over time and that revaccination is needed to maintain immunity. [Mack TM. Smallpox in Europe, 1950-1971. J Infect Dis 1972; 125:161-169]

Last Updated: February 27, 2024
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