Because of the recent increase in global terrorist activity, governments around the world have become concerned that terrorists might use smallpox as a weapon. If a terrorist were to release a small amount of the virus into the air, it is possible that it could spread among a large number of people. The virus could survive and infect people for 6 to 24 hours, depending on the weather.

In early 2001, the United States government increased its preparedness for a smallpox outbreak and took steps to expand its vaccine stockpile. The U.S. has enough smallpox vaccine to vaccinate Americans in an emergency.³

Smallpox (vaccinia) vaccine (What is a PDF document?) is recommended for laboratory personnel who work with the vaccinia virus, for members of smallpox response teams, and for certain members of the military. Vaccination is not currently recommended for the public. For accurate, up-to-date information, visit the Centers for Disease Control and Prevention (CDC) Web site at http://www.bt.cdc.gov/agent/smallpox.

Special-risk populations

Certain people have a higher risk of having complications from the vaccine and should not be vaccinated unless they are exposed to smallpox. These include:

• Pregnant women, because of the risk of infecting the fetus.
• Breast-feeding women, because of the risk of infecting the baby.
• People with skin conditions, such as active or healed eczema.
• Children younger than age 1.
• People who have an impaired immune system.
• People with serious, life-threatening allergies (anaphylaxis) to the antibiotics polymyxin B, streptomycin, tetracycline, or neomycin.
• People who have household contact with someone who has an impaired immune system, is pregnant, or has certain skin conditions, such as active or healed eczema.

If you have heart problems or three or more risk factors for heart disease, you should not be vaccinated until more is known about a possible relationship between the smallpox vaccine and heart problems, including heart attack.

But if you are directly exposed to smallpox, you should be vaccinated even if you fall into one of these groups.⁵ In such a situation, the risk of death from smallpox is greater than the risk of having a harmful reaction to the vaccine.