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Treatment for Smallpox

Smallpox has no known treatment. Using the smallpox vaccine within three to four days of exposure can help reduce the severity of smallpox disease, and in some cases even prevented it. 

Beyond that, medical care aims to ease symptoms such as fever and body aches, as well as control other illnesses that can develop when the immune system has been weakened by smallpox. 

Research efforts continue to explore antiviral drugs as possible treatment for smallpox.

Prevention: The Smallpox Vaccine

The smallpox vaccine uses the cousin virus to variola -- the vaccinia virus -- because it poses fewer health risks. The vaccine stimulates the body's immune system to create antibodies that protect against the variola virus and prevent smallpox disease. 

No data exists proving how long the smallpox vaccine protects against smallpox. Some experts believe the vaccine lasts for 10 years, with less protection as the years pass. Since the vaccine has not been proven to provide lifelong protection, anyone vaccinated years ago as a child could theoretically be at risk of future infection by the variola virus. The only people known to be immune for life are those who have had smallpox and survived. 

The WHO and its member countries keep an emergency stockpile of the smallpox vaccine. The vaccine is rarely used today, except for those few people at risk of being exposed to the variola virus, such as laboratory researchers working with variola and similar viruses. No countries today give routine smallpox vaccinations to the public.

Risks of the Smallpox Vaccine

Reactions to the vaccine can be life-threatening, especially for people with immune system deficiencies. Adverse reactions range from skin reactions to a serious central nervous system condition called encephalitis, which can lead to convulsions, coma, and death. Based on historical data, for every 1 million people vaccinated, one person died from an adverse reaction to the smallpox vaccine. 

Some people would have a higher risk of an adverse reaction to the vaccine. These include women who are pregnant or breastfeeding; people with the skin disorders such as eczema; people with a compromised immune system due to a medical condition like leukemia or HIV; and people on medical therapies, such as for cancer, that suppress the immune system.


Smallpox as a Public Health Threat

In recent years, acts of terrorism have renewed international concern that biological agents such as the smallpox virus could be used in an act of bioterrorism to start a smallpox epidemic in a target country. The public health threat of a smallpox outbreak today is hard to quantify for several reasons:

  • The worldwide population of immune-compromised people is higher today than when smallpox existed.
  • Different potencies of vaccine were used in different countries during the global effort to end smallpox.
  • The length of immunity from these different vaccinations can't be known for sure. 

If an outbreak of smallpox were to occur for any reason, public health measures would include identifying and vaccinating people infected with smallpox; vaccinating health care workers and others at risk of infection; isolating smallpox patients to help prevent further transmission; and vaccinations available to the public as needed to contain the outbreak.


WebMD Medical Reference

Reviewed by Varnada Karriem-Norwood, MD on October 11, 2012

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