But by making immunization voluntary, the White House has left Americans in the difficult position of having to weigh the theoretical risks of a smallpox attack with the small but concrete odds of suffering a serious or deadly side effect from the vaccine.
Under the Bush plan, expected tomorrow, as many as a half million soldiers will be required to receive the vaccine. They will be followed by up to about 10 million health and emergency personnel, the so-called "first responders" charged with immunizing others and containing infections in the event of an attack with the frequently deadly virus.
The rest of the nation will have the option of getting vaccinated, possibly beginning in 2004. The smallpox vaccine is effective against the virus, but it can lead to deadly complications in about one in every 1million people who receive it. Another 10 to 15 per million suffer serious side effects, such as severe rashes.
"I think it ought to be a voluntary plan. I don't think people ought to be compelled to make the decision which they think is best for their family," Bush told ABC News in an interview that aired in part yesterday.
Two-thirds of Americans say they'd receive the smallpox vaccine despite the risk of serious side effects, according to a new poll by the Robert Wood Johnson Foundation.
The Bush plan differs from early thinking about the best vaccination strategy for smallpox. First reports suggested that the total number of people who would be offered the inoculation -- which involves scratching weakened vaccinia virus beneath the skin with a tiny fork-like device -- would be 15,000.
The United States abandoned routine immunization against the virus in 1972, and the World Health Organization declared the infection eradicated in 1980. However, the United States and Russia have preserved samples of the virus, and intelligence experts fear that Iraq and North Korea have supplies of it, too.
Health officials are now stockpiling enough doses of smallpox vaccine to immunize the entire country if needed. Roughly 60 percent of the population alive today was born before routine smallpox vaccination ended, but scientists don't know how much protection they may have retained. A study of 900 people is now under way to determine just that.
So should you get the vaccine when it's available? And what if you already were immunized?
"I would not personally consider that I am protected even though I had a shot as a child," said Edward Kaplan, a Yale University smallpox vaccine expert. On the other hand, he added, people who've already been immunized are probably less likely to suffer side effects the second time around.
Pregnant women, people with HIV and AIDS, and those with certain skin conditions shouldn't be given the smallpox vaccine in a pre-attack inoculation program. Whether they choose to do so during an outbreak depends on the scope and severity of the attack, Kaplan said.
Kaplan said he believes a voluntary system for the general public is the right approach. But making the decision to get inoculated will require careful thinking and cost-benefit analysis. "It sort of depends on what the post-attack planning is in your state," Kaplan said. "In some places I have more confidence than in others."
The Centers for Disease Control and Prevention announced today that it has reviewed smallpox vaccination plans from 49 states and four cities. The plans, which vary by jurisdiction, outline where the shots would be administered. According to the CDC, the vaccine will be available at 3,300 health-care facilities and hundreds of clinics nationwide.
Kaplan said some states are considering a strategy of "ring vaccination," in which a small group of first responders is tasked with trying to contain an outbreak by inoculating as few people as necessary. That approach, he said, makes him nervous.
"If I was in a state where that was the agreed-upon policy, I would think very hard about getting vaccinated on a voluntary basis," said Kaplan, who strongly prefers a much broader tack where an entire city would be offered the protection. Ironically, the more people who opt for vaccination, the more prudent waiting becomes, since those who do get the vaccine serve as a buffer for the rest.
But not every expert agrees with the Bush decision. Dr. John Neff, a pediatrician at the University of Washington who has studied smallpox, said the public doesn't need to be vaccinated before an outbreak.
"Right now, unless we know more about what the President is thinking, I think that the potential risk from an adverse event is higher than from getting and dying from smallpox," Neff said. "The first line of defense makes a certain amount of sense. To have everybody get it on their own choice makes no sense," said Neff, who argues that the Bush decision was driven more by the looming war in Iraq than consideration about what's scientifically appropriate.
Unnecessarily encouraging mass inoculations might have devastating repercussions in the rest of the world, said Neff. The United States can control an outbreak within its borders, but it almost certainly can't keep the infection within them, he said. Although Europe might have enough vaccine to quash a limited smallpox outbreak if it crops up there, South American nations almost certainly do not.
"If we use [vaccine stocks] up by having unnecessary vaccinations we would not be looked upon favorably by the rest of the world and we couldn't help them," Neff said.
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