Smallpox Disease and Vaccine

by Food and Drug Administration (FDA)

The last confirmed case of smallpox in the United States occurred in 1949, and the last naturally occurring case in the world was recorded in Somalia in 1977. Three years later, the World Health Organization declared that smallpox had been eradicated. But if terrorists were to intentionally introduce just a single case of smallpox today, it could mushroom into a public health emergency, experts say.

In December 2002, President Bush announced a comprehensive plan to protect Americans from smallpox if it were to be used in a bioterrorist attack. The plan addresses actions to quickly contain an outbreak through vaccination. As part of this plan, the U.S. Department of Health and Human Services (HHS) has been working with state and local governments to develop a national stockpile of smallpox vaccine.

The only smallpox vaccine currently licensed by the Food and Drug Administration is Dryvax (smallpox vaccine, dried, calf lymph type), made by Wyeth Laboratories Inc. in Marietta, Pa. "The vaccine was first approved in 1931, and the existing lots were manufactured in the 1970s and early 1980s and stored frozen," says William Egan, deputy director of the FDA's Office of Vaccine Research and Review. "The vaccine lots remained fully potent."

In October 2002, the FDA approved a license supplement for a 100-dose kit of Dryvax, with a new supply of diluent (the liquid that's mixed with dried vaccine before it's administered) and needles for administration, Egan says. "Before the approval of this supplement, Dryvax was available only under an investigational new drug (IND) application. Now the vaccine can be distributed and used as any other approved product." Along with Dryvax, there are several other smallpox vaccines that are being evaluated under INDs.

The potential threat of smallpox as a biological weapon has raised plenty of questions about the disease and the vaccine. Here are some answers from the FDA and the Centers for Disease Control and Prevention (CDC).

Q. Does smallpox pose a significant threat as a weapon?

A. There is no proof of any threat right now, but the CDC recognizes it as a possibility. In light of the terrorist attacks in September and October 2001, including the use of anthrax, the smallpox plan was developed as a precautionary measure. Smallpox is particularly dangerous because it can be spread from person to person, has a high rate of mortality, and there is no known cure (although it can be prevented through vaccination).

Q. How is smallpox spread?

A. Smallpox is caused by the variola virus, which is spread through close contact with a person who has symptoms of the disease. A person with smallpox has infected saliva, and face-to-face contact can spread the virus. The virus could also be spread through other body fluids and contaminated clothing or bed linen. Smallpox is highly contagious, and people who have it are most infectious during the first week of illness.

Q. What are the symptoms of smallpox?

A. The first symptoms of smallpox usually appear between a week and 17 days after exposure to the virus, and can include high fever, fatigue, headaches, backaches, and vomiting. The next symptom, which appears in the next two to three days, is a rash on the face, arms, legs and other areas of the body. The rash turns into raised bumps that become pus-filled blisters. Scabs develop and usually fall off three to four weeks later.

Q. How dangerous is smallpox?

A. The CDC classifies smallpox as a Category A agent, a designation given to diseases believed to pose the greatest threat to public health. Anthrax, botulism, and plague are also in this category. Up to 30 percent of smallpox cases result in death, and the death rate can be higher in infants and small children. The remainder of people who contract smallpox recover, though they are often left with permanent scarring and sometimes blindness.

Q. How is smallpox treated?

A. No proven treatment exists. People with smallpox are given intravenous fluids and medicine to control fever and pain, and antibiotics are given to prevent or treat possible bacterial infections. Two treatments for smallpox — Vaccinia Immune Globulin (VIG) and cidofovir — are being studied and could be given under investigational new drug protocols.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.