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Smallpox I: CDC Using Some Guesswork, Official Says By David Ruppe Global Security Newswire The U.S. Centers for Disease Control and Prevention decision Monday not to vaccinate the entire U.S. population against smallpox relied on some difficult assumptions, a senior U.S. official and other experts told Global Security Newswire. Some of the agency’s premises are that the risk of a smallpox attack involving significant casualties is low and that the nation’s public health officials would be able to promptly identify and contain an attack and treat the victims. The CDC said the risks from side effects in mass vaccination are not warranted, given the low probability of an attack (see GSN, Nov. 27). It recommended instead a strategy of containing an outbreak, using rapid surveillance and vaccination of suspected victims, but D. A. Henderson, director of the U.S. Department of Health and Human Service’s Office of Public Health Preparedness, acknowledged the difficulty in making such assumptions. “In doing a cost-benefit analysis, we’re looking at a very difficult problem, because we’re looking at on one side a probability of events which we really can’t quantify: the likelihood of a disease occurring, smallpox being reintroduced,” he said. “You can’t really come up with a quantitative measurement of cost-benefit, it’s got to be a kind of best guess based on what we know.” The CDC concluded that the risks from a mass vaccination—which would cause severe side effects in a small, but significant, percentage of the population—outweighed the probability of a smallpox attack. Most experts agree. They cite the limited availability of the virus worldwide since a World Health Organization-led effort successfully eradicated it from nature in the late 1970s. Weighing the Probability of an Attack There are only two known sites that still have the smallpox-causing variola virus: the CDC in Atlanta and a Russian facility in Novosibirsk. Other countries, however, also are suspected of having the virus, although there is no hard evidence (see related GSN story, today). A smallpox attack might also be unlikely because of the difficulty in using the virus as a weapon, Henderson said. “It really has to take a bit of attention, in terms of keeping it cool and in some sort of condition,” he said. “Trying to dry it out and make it a powder is much more complicated than with anthrax. You put it all together, there are much more barriers there than with anthrax. “The best we can do is say—and I think there’s a general feeling—that it’s an unlikely event, and I think fairly unlikely,” he said, adding, “but it’s not zero…and were it to be released, you’re faced with some very serious problems unlike any other disease I can think of.” Anticipating the Severity of an Attack Another unknowable factor is the severity of any future outbreak. While a small outbreak might be easily contained, a large-scale outbreak, perhaps surfacing in numerous cities, could overwhelm the system, experts say. Last summer in a tabletop exercise named “Dark Winter,” multiple releases of the virus in several cities overwhelmed the public health system and produced 3 million fictional victims and 1 million deaths. Dark Winter participants, which included former government officials, identified problems such as insufficient vaccine and an unprepared surveillance, response and public health infrastructure. A successful response could “depend upon how many are in the initial outbreak. It could be one [victim], it could be 10, it could be more,” said Amy Smithson, a senior associate at the Henry L. Stimson Center. Jonathan Tucker, a chemical and biological weapons analyst at the Monterey Institute of International Studies and author of a recently published book on smallpox, questioned whether the nation’s infrastructure would be able to handle a severe attack. “One assumption that this plan relies on is a very good disease surveillance capability, so that you could detect an outbreak at an early stage so that it doesn’t spread very far,” he said. “I think [the CDC] plan makes sense if we strengthen our public health system appreciably. I think if we had an outbreak of smallpox today under present circumstances, we might not be able to detect it early enough to contain it readily.” Calls for Mass Vaccination In the wake of the Sept. 11 attacks against the United States and subsequent mailings of anthrax, there have been some calls for a mass smallpox vaccination of the U.S. public. The Bush administration is contracting to procure from a private company enough vaccine for every U.S. citizen, bringing the U.S. stockpile of vaccine doses to 286 million. Health and Human Services Secretary Tommy G. Thompson announced Tuesday a $428 million contract to produce 155 million doses of smallpox vaccine by the end of 2002 (see GSN, Nov. 29). Some lawmakers have pressured the administration to mass-vaccinate. Senator Arlen Specter (R-Pa.), in a hearing this month, called the administration’s stated time frame for procuring the doses “inadequate” and indicated he favored preventive vaccination. “My judgment would be to have my four granddaughters vaccinated. It's one in a million that they're going to have an adverse reaction,” he said. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, also at the hearing, seemed to agree. “What you say makes very good sense, Senator. And as a matter of fact, myself personally, my own children, I would take the risk of getting them vaccinated, if we were given the choice of having it.” Even experts who oppose vaccinating the population as a preventive measure seem to agree that having nearly 300 million doses on hand would be a good precaution. Were a massive outbreak to occur, they say, the vaccine could effectively prevent the disease if provided to large numbers of people up to three days after they have been exposed to the virus. “This new contract gives us the insurance that we will have more than enough vaccine for any outbreak that might occur,” Thompson said in a statement Wednesday. Improved Surveillance Needed To make the CDC’s containment strategy work, the nation’s public health system needs strong surveillance and rapid response capabilities, according to the experts. That is going to require some improvements, Tucker said. “There are a lot of gaps in the system. For one thing, our surveillance systems are not that good.” “Our physicians have for quite some time not had as a basic requirement of their medical training an intensive dose of infectious disease recognition and treatment,” said Smithson. “Only infectious disease specialists have had that type of training, and even those specialists often have not encountered those more exotic diseases,” she said. The CDC’s plan announced Monday calls for such education, and a range of other infrastructure improvements, including preparing local health care providers across the country to rapidly administer large numbers of vaccinations. CDC bioterrorism preparedness expert Lisa Rotz said Monday that the agency currently could deliver vaccine anywhere in the country in a matter of hours. The CDC also is preparing materials for mass distribution to help physicians better identify the disease. “This material is just now getting out there,” said Henderson. Asked when all the reforms might be implemented, Rotz said the CDC’s plan was released “so state and local health officials can start thinking through these issues from their local perspective and how they would start implementing the control measures very rapidly.” She said, “Obviously, certain parts of the plan would take longer to implement.”
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