The U.S. government can't guarantee that such an attack won't occur, but it will soon have the means to thwart the terrorists. By the fall, U.S. stockpiles of smallpox vaccine will reach nearly 300 million doses, enough for the entire population. Then, the Bush Administration will have to choose among a range of options. It can permit the vaccination of up to 20,000 medical personnel, as recommended on June 20 by an advisory medical panel. Or it could heed Richard Levinson at the American Public Health Assn. and "immunize everyone as quickly as possible." The best approach, however, is a middle path that has received little attention: allow carefully screened, healthy adults to volunteer for vaccination. "The more volunteers you vaccinate, the slower the spread of any disease through the general population, and the more time you have to vaccinate the rest," says William J. Bicknell at the Boston University School of Public Health.
For now, the government plans to stick with a tried-and-true approach called "ring containment." The idea: treat the sick and vaccinate anyone they may have come in contact with. This approach was last used in the U.S. in 1947 when an infected businessman arrived from Mexico by bus in New York City. Authorities vaccinated more than 6 million people in a month. Only 12 contracted the disease, and just two died.
The trouble is, ring containment is based on a chance outbreak, not a terrorist attack. "It is not going to work against a thinking agency like al Qaeda in a highly mobile, concentrated, and unvaccinated society," says Randall J. Larsen, director of the ANSER Institute for Homeland Security, a Washington think tank. Forced to respond to a series of attacks in different cities, health officials would be quickly overwhelmed.
So why not just vaccinate everyone and stop worrying? Two big reasons: Scientists estimate that mass vaccinations could lead to unacceptably high rates of complications--up to four deaths per million from encephalitis and other maladies, as well as lesser skin rashes. Secondly, the vaccine is itself a live virus, albeit far less harmful than smallpox, and it's contagious. In past immunization programs, 20% of those suffering vaccine-related symptoms had not been inoculated themselves. "That's what makes it a societal decision and not just a personal choice," says D.A. Henderson, a U.S. scientist who led the worldwide fight to stamp out smallpox in the 1970s.
The middle path addresses both objections. Screening out people whose immune systems are already damaged by AIDS or cancer treatments, while barring young children, could cut vaccine-related deaths to an estimated one in a million, says Bicknell. In addition, vaccinated volunteers would naturally produce a substance in their blood called vaccinia immune globulin, which could be harvested and administered as a therapy to people suffering mild complications.
The risk of a terrorist attack can't be quantified. But homeland security experts note ominously that both Iraq and North Korea vaccinate at least some of their military, suggesting that they may have stockpiles of smallpox. And Russians once produced tons of highly weaponized forms of the virus, some of which may now be in terrorists' hands.
There are no easy answers, allows Henderson. He advocates a cautious approach, noting that "this is a risk-averse society." That's true. But it's also why the government ought to allow some voluntary vaccinations, and let people decide for themselves if the risk is worth the taking. Magnusson covers homeland security from Washington, D.C.