Countering the Smallpox Threat
Even before the September 11 attacks heightened our fears of bio-terrorism, a biologist came up with a sensible strategy for coping with one of the most fearsome possibilities
In the days following the terrorist attacks that brought down the World Trade Center and demolished part of the Pentagon, I received a series of e-mails from my sister asking what I thought she could do to protect herself and her family. Should she stock up on water? On food? What about buying a gas mask? I told her I doubted that any of those things would really help. At first blush the notion of suburban moms buying gas masks seemed a little silly. But a lot of people were buying gas masks at that point, and mostly they were not silly people, and the impulse they were acting on was not silly. What they wanted was to do something: to exert at least a little control over a new and frightening situation. That is just the sort of impulse that the fight against terrorism needs to put to use. One way to use it is against the threat of smallpox.
Experts have agreed that smallpox terrorism is potentially the Big One. Maybe not bigger in terms of lives lost than, say, a nuclear warhead detonating over Manhattan, but certainly right up there, and probably more socially destabilizing. Unlike chemical agents and some other biological agents, such as anthrax (as we've lately seen) and botulism, smallpox spreads virulently from person to person. The disease is fatal 30 percent of the time and leaves its survivors disfigured and sometimes blind. Symptoms take a week or two to appear. In an urbanized country full of planes, trains, and automobiles, smallpox could easily spread to any number of cities and states before health officials realized what was going on.
Routine smallpox vaccination ended in the early 1970s, because a worldwide campaign had succeeded in eradicating the disease. The virus survived only in laboratories in the United States and the Soviet Union. After the Soviet Union collapsed, credible reports surfaced alleging that the Soviets had produced smallpox in large quantities, for biological warfare. Bio-terrorism experts began to worry that the Russians might have let the virus slip into the wrong hands. Still, most people believed that smallpox's very virulence made it an unlikely weapon of terror. After September 11 a lot of those people changed their minds.
I was vaccinated for smallpox years ago, in childhood; so were many other Americans who are now over thirty. But it's unclear how much good this would do if smallpox were unleashed today. "One of the problems with smallpox vaccine is that immunity doesn't last very long," Peter J. Hotez, a senior fellow at the Sabin Vaccine Institute, in Washington, D.C., told me when I asked if I would be safe. "It can last as few as three to five years." And younger people, of course, weren't vaccinated. America today would be a tinderbox for smallpox: something like 90 percent of the population is thought to be susceptible.
To its credit, the Clinton Administration took the threat seriously. Realizing that existing stocks (about 12 million to 15 million doses of twenty-year-old vaccine) were too thin to cope with a serious crisis, in September of last year the government ordered up a new smallpox vaccine, with the first 40 million doses to be delivered in 2004 and more to come thereafter. This October, as anthrax scares transformed the threat of bio-terrorism into reality, the Bush Administration announced that it would seek to increase the smallpox-vaccine inventory to 300 million doses, possibly by next year.
With the new vaccine will come a new and difficult question: Who should be vaccinated? My first thought was "Everyone." Or at least—as Homeland Security Chief Tom Ridge has suggested—we should resume routine vaccination of children. But this sort of uniform approach has a significant drawback. The smallpox vaccine is not perfectly safe. During the eradication campaign, according to Tara O'Toole, of the Johns Hopkins School of Public Health, about one in 300,000 people died from side effects of the vaccine or suffered irreversible brain damage. At that rate, if all 280 million Americans were to be vaccinated, nearly a thousand people would die or be gravely injured.
For that reason the government instead built its plans around a containment strategy. Vaccine would be stockpiled for use in case of an outbreak. If smallpox were spotted, authorities would declare a health emergency and rush to vaccinate (or quarantine) everyone likely to have crossed the virus's path. (Fortunately, the vaccine is effective even when given a few days after exposure, so in principle post-outbreak vaccination could stop the spread.) There is certainly something to be said for the containment strategy, but it is not without worrisome risks. It relies on health workers, public officials, and the public itself to react quickly, calmly, and efficiently. Virtually everyone who was exposed would need to be promptly vaccinated or quarantined. That would be easier said than done, because the early symptoms of smallpox look like flu. Moreover, once word of a smallpox outbreak hit the street, panic, chaos, flight, and human error would inevitably give the virus chances to spread. Even if a containment plan ran like clockwork, some people—those caught at the onset—would die who might have lived had they previously been vaccinated.
While I was pondering these problems, I came across a news article from October of 2000, in which a biologist named Paul W. Ewald, of Amherst College, suggested something so obvious that no one else seemed to have considered it. He proposed making the smallpox vaccine available to the public, the way many other vaccines are today. Individuals could then decide, after being apprised of the risks and with medical advice, whether or not to get themselves and their children inoculated.
Regular readers of this magazine may recall from an article in the February, 1999, issue—"A New Germ Theory," by Judith Hooper—that Ewald has specialized in thinking about how doctors can use evolutionary pressures to make pathogens more benign, and how terrorists might contrive to make pathogens deadlier. That led him to think about smallpox. I called Ewald recently and asked him to expand on the idea of voluntary vaccination.
"I think the key thing that's been missed in this analysis," he told me, "is that the more any given vaccine is used, the less bang the terrorist is going to get." Even if only a minority of the public chose vaccination, those people's immunity would not only protect them in the event of an attack but would also slow transmission to others. That could buy precious time. Moreover, if, say, 30 million people were vaccinated, there would be 30 million fewer to vaccinate in a crisis. Indeed, Ewald said, "If you have thirty million people vaccinated, the terrorists might just decide, Let's not bother." The terrorists might, of course, try something else—but pretty much anything would be better than smallpox.
"Another problem," Ewald said, "is that if you wait until the crisis is at hand, you lose a chance to have careful analysis on a patient-by-patient basis of the risks posed by vaccinating. It might just be that you're cranking out vaccinations as fast as possible." There is a deeper point here as well. People are as different in their tolerance for risk as they are in their tolerance for vaccines. To weigh the minuscule but real risk of a smallpox attack against the minuscule but real risk of complications from a vaccine is to weigh imponderables. No public-health expert is any more qualified to make this call than is the person who will have to live with the consequences.
It isn't surprising that it was a biologist who suggested letting individual people and doctors, rather than public-health authorities, decide who would be vaccinated. Biologists tend to see a world of variegated individuals, whereas the public-health establishment tends to view the public as a "population" and to think in terms of centralized, one-size-fits-all measures based on expert knowledge. A national anti-terror campaign will certainly need its share of unitary, top-down strategies on the public-health and national-defense models; but if it is to be sustainable and successful it will need to treat the public first and foremost as a resource to be enlisted, not merely as a population to be instructed. As we know from United Airlines Flight 93, engaging the intelligence and moral judgment of ordinary people can make all the difference. Why not apply that lesson to the greatest terrorist threat of all?