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Prevention and Treatment

There is no proven treatment for smallpox disease, but some antiviral drugs may help treat it or prevent it from getting worse. There also is a vaccine to protect people from smallpox. If there were a smallpox outbreak, health officials would use the smallpox vaccine to control it.

Smallpox Vaccine

Smallpox can be prevented by the smallpox vaccine.

If you get the vaccine:

  • Before contact with the virus, the vaccine can protect you from getting sick.
  • Within 3 days of being exposed to the virus, the vaccine might protect you from getting the disease. If you still get the disease, you might get much less sick than an unvaccinated person would.
  • Within 4 to 7 days of being exposed to the virus, the vaccine likely gives you some protection from the disease. If you still get the disease, you might not get as sick as an unvaccinated person would.

Once you have developed the smallpox rash, the vaccine will not protect you.

Currently, the smallpox vaccine is not available to the general public because smallpox has been eradicated, and the virus no longer exists in nature. However, there is enough smallpox vaccine to vaccinate every person in the United States if a smallpox outbreak were to occur.

For more details about the vaccine, see Smallpox Vaccine Basics.

Antiviral Drugs

  • In laboratory tests, Tecovirimat has been shown to be effective against the virus that causes smallpox. In laboratory settings this drug was effective in treating animals which had diseases similar to smallpox. Tecovirimat has not been tested in people who are sick with smallpox, but it has been given to healthy people. Test results showed that it is safe and causes only minor side effects.
  • In laboratory tests, Cidofovir and Brincidofovir have been shown to be effective against the virus that causes smallpox. In laboratory settings this drug was effective in treating animals which had diseases similar to smallpox. Cidofovir and Brincidofovir have not been tested in people who are sick with smallpox, but they have been tested in healthy people and in those with other viral illnesses. Test results indicate that Brincidofovir may cause fewer side effects than Cidofovir, which can be toxic to kidneys.
  • Because these drugs were not tested in people sick with smallpox, it is not known if a person with smallpox would benefit from treatment with them. However, their use may be considered if there ever is an outbreak of smallpox.
  • Tecovirimat and Cidofovir are currently stockpiled by CDC’s Strategic National Stockpile, which has medicine and medical supplies to protect the American public if there is a public health emergency, including one involving smallpox.
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