Short-circuiting Smallpox

Government working to expand vaccine reserves and antiviral drug use

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By
HealthDay Reporter

FRIDAY, Oct. 19, 2001 (HealthDayNews) -- Bracing for future bioterrorism even as anthrax still is center stage, the government today announced it is pursuing two avenues to protect the nation against smallpox.

Stretching the existing supply of smallpox vaccine and expanding the use of an AIDS antiviral drug may be the first lines of defense against the disease, a scourge of the Middle Ages that was declared eradicated in 1980 by the World Health Organization, the government says.

"We have 15 million doses of smallpox vaccine in our reserve, and our immediate plan is to understand how we amplify those doses to make them much, much more," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, at a press conference today in Washington, D.C. "What we are testing is whether you can dilute the vaccine, but what we don't know is whether diluting the vaccine to one in five or one in 10 will provide protection."

To determine if a diluted vaccine will work, the government has asked for help from four centers: the University of Rochester in New York, Baylor University College of Medicine in Waco, Texas, the University of Maryland in College Park and the Saint Louis University School of Medicine in St. Louis, Mo. "We should have results in a couple of months and should be ready by the end of the year," Fauci said.

"You have to wait to see whether the classic things happen with the diluted vaccine that would happen with a regular vaccine. Will it produce a pustule, a scab and then a scar? If it does those things, that's indicative of the vaccine's [effectiveness]. What you can't do is expose someone to smallpox -- that would be unethical, obviously. So if you can't determine it that way, to find out if it's effective, you make the assumption that if looks and acts like the old vaccine, then it works," said Fauci.

Smallpox is a highly contagious disease caused by the variola virus. The virus has been known for thousands of years and over the centuries probably has killed up to 100 million people and left 200 million blind and scarred. Smallpox begins with a sudden fever, headache, backache, vomiting, complete exhaustion, even delirium. Small, red, pimple-like bumps, or pustules, appear seven to 17 days after exposure to the virus, eventually developing into blisters that scab and scar. People are contagious from the time the rash appears, particularly in that first week of illness, until the scabs fall off.

Fauci said another drug, cidofovir, may be effective against smallpox. The drug is used to treat a viral infection of the eyes in AIDS and HIV-infected patients.

"In animal models and pre-clinical trails, cidofovir has proven effective against the smallpox virus, though it has not been used in a smallpox situation, since no such situations have been available. We are gearing up for an investigational drug exemption to use in studies as a potential backup for the vaccine," but there is no guarantee the drug will work, Fauci said. Approved by the FDA in 1996, cidofovir is marketed as Vistide by Gilead Sciences of Foster City, Calif. A 1998 study found that it worked well against the monkey version of smallpox. Adverse reactions to the drug range from kidney problems and fever to nausea.

If you were vaccinated against smallpox in the past, you may not be out of the woods. Immunity after vaccination will last 10 years, but only with boosters shots, according to the National Network for Immunization Information.

Is the government planning on vaccinating everyone in the United States?

"We have short-term, intermediate and long-term plans," Fauci said. "We're scaling up the production of smallpox vaccine right now, and we should have enough of the vaccine in six to 10 months. The question is: Would you preemptively vaccinate everyone at that point?"

That depends on whether there were a real threat or an actual smallpox event, said Fauci. "There's no question you would quarantine and vaccinate everyone around,"

Even so, every vaccine carries a risk.

"You can have an overwhelming reaction from the vaccine where the pustules are not confined to the five millimeters around the vaccine site but are disseminated throughout the body," Fauci said. Or you can pass the vaccine itself into the open wounds of another person. "There's even a gangrenous response to the vaccine. The vaccine is certainly beneficial and effective, and while the toxic side effects are very rare, when they occur, they are very dangerous."

What To Do

For more on the smallpox vaccine, see the Immunization Action Coalition. For a rundown on its use as a biological threat, check this article from The Journal of the American Medical Association.

And here's a history of the disease.

SOURCES: Anthony Fauci, M.D., director, National Institute of Allergy and Infectious Diseases; Oct. 19, 2001, National Foundation for Infectious Disease press conference, National Press Club, Washington, D.C.

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