United States: For 60 Million, the Cure May Kill

About 60 million people in the United States have conditions that leave them essentially defenseless against vaccinia, the live virus used to make smallpox vaccine. They include people with HIV/AIDS or other immune deficiencies, people who have had organ transplants, cancer patients undergoing chemotherapy, and people with eczema and certain other skin diseases. Health professionals also advise against vaccinating pregnant women, because no one knows how vaccinia might affect fetuses.

Although vaccinia is generally easily conquered by a healthy person's immune system, it can have life-threatening side effects -- even in healthy people. Research in the 1960s found that 12 people per million developed encephalitis after vaccination. One or two per million die. Widespread vaccination would cause about 4,600 serious side effects and 285 deaths.

Those with undiagnosed conditions, including about 300,000 people in the United States with undiagnosed HIV, face the greatest risks: Simple contact with someone just vaccinated could infect some of them.

Health authorities cannot accurately balance the risks of vaccination against the likelihood of a smallpox outbreak. Until a case appears, the risk of vaccination will always be greater than the risk of getting smallpox.

"Experts are worried," noted Tara O'Toole of the Center for Civilian Biodefense at Johns Hopkins University's Bloomberg School of Public Health, "that a general vaccination program will inevitably cause some lethal side effects ... [that will] demolish the public's faith in vaccination and in following the government's bioterrorism recommendations."

The Bush administration's vaccination plan being released today represents a relatively small-scale beginning to mass vaccinations. But even a limited program could unleash vaccinia among people without defenses to it.

Doctors can treat severe vaccine reactions with vaccinia immune globulin (VIG), antibodies drawn from the blood of inoculated people. However, only 600 doses of VIG exist. The government has ordered about 30,000 more.

Cidofivir, licensed to treat retina infections in people with HIV/AIDS, might be another option, doctors say. Cidofivir alone, or combined with VIG, could make smallpox the latest virus yielding to treatment.

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