Doctors: Smallpox vaccine can be increased

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Posted 8:36AM on Friday, March 29, 2002

WASHINGTON - Doctors can safely dilute the nation's 15.4 million doses of smallpox vaccine to make up to 10 times more inoculations, according to new research that comes as the government attempts to buy still millions more doses discovered in a drug company's freezers. That means there could be a bigger inventory of vaccine in case of a bioterrorist attack than previously realized. And that's before some 200 million brand-new doses ordered from a British manufacturer roll off the production line later this year. ``We hope our smallpox vaccine stockpile will serve as a deterrent to those who may consider using smallpox as a weapon,'' said Health and Human Services Secretary Tommy Thompson. ``We will have the necessary medicine to save and protect every American should there be an outbreak.'' But that doesn't mean it's nearing time for mass vaccinations, cautioned Dr. Anthony Fauci, infectious disease chief at the National Institutes of Health. The vaccine can cause some severe, even fatal, side effects. Scientists believe if everyone were vaccinated, anywhere from 180 to 400 people would die. ``If we could vaccinate people with virtually no incidence of any serious toxicity ... we tomorrow could eliminate the threat of a smallpox bioterrorist attack. Unfortunately that is not the case,'' Fauci said. But he welcomed public debate on the issue, particularly about whether emergency workers who might be first exposed in a smallpox attack should be vaccinated. The nation quit routine smallpox vaccination in 1972, and the disease was declared eradicated worldwide in 1980. But the U.S. and Russian governments hold stocks of the deadly virus, and bioterrorism experts worry that samples could fall into terrorists' hands and be used as a weapon, although Thompson stressed Thursday the risk is low. Still, the government is buying up vaccine as a precaution. If an attack occurred, doctors would quickly vaccinate people in the vicinity, because inoculations up to four days after exposure still offer protection. Already stockpiled are 15.4 million doses left over from the 1970s. That vaccine could be diluted, turning each dose into five to 10 additional doses, and still protect, say two studies released Thursday by The New England Journal of Medicine. The studies of more than 700 previously unvaccinated young adults found about 97 percent responded to diluted or undiluted inoculations, although some required two doses. No one became severely ill. But one person had blister-like lesions erupt over a swath of his body. More than a third had pain bad enough to miss school, work or other activities. Fever, headache, nausea, muscle aches, lesions and swelling were fairly common. One catch: A few people never responded, and blood tests suggest they had been vaccinated decades earlier and forgotten. Thus, more study is needed to tell if diluted vaccine can boost the presumed waning immunity of millions vaccinated 30 years ago. To be conservative, the 15.4 million doses will be stretched only to 77 million, not the full dilution possible, Fauci said. In another development, Pennsylvania-based Aventis Pasteur last fall told the government it had 70 million to 90 million doses of smallpox vaccine sitting in its freezers. Aventis now is checking whether that vaccine still is effective, and Thompson is negotiating to buy it. ``We expect this to turn out to be some further good news,'' but negotiations aren't completed yet, Thompson said.