At only 200 nanometers, the brick-shaped smallpox virus is not intimidating in size. The implications of a smallpox attack as a form of bioterrorism, however, are much larger. Imagine the following scenario described in the 1999 report “Smallpox as a Biological Weapon” from the Journal of the American Medical Association: “a clandestine aerosol release of smallpox, even if it infected only 50 to 100 persons to produce the first generation of cases, would rapidly spread in a now highly susceptible population, expanding by a factor of 10 to 20 times or more with each generation of cases.” Though actual predictions vary from source to source, the severity of a smallpox attack could potentially be devastating. The U.S. Centers for Disease Control and Prevention (CDC) classify smallpox as a Category A agent, meaning that it spreads easily, causes “public panic and social disruption,” and has a high death rate.
Thanks to a worldwide smallpox vaccination campaign, naturally occurring smallpox was successfully eradicated. According to the CDC, the last reported case occurred in Somalia in 1977, and the virus has not infected anyone in the United States since 1949. However, public interest in bioterrorism—defined as a deliberate release of biological material that causes sickness or death in humans, animals, or plants—grew rapidly between the 2001 anthrax attacks and the United States’ invasion of Iraq in 2003. Today, the smallpox virus is kept in only two labs in the United States and Russia. Despite this, a certain degree of concern exists that other groups could have acquired the smallpox virus. Edward H. Kaplan, a professor of management sciences, public health, and engineering at Yale University, said in an interview that although he believes the probability of a smallpox attack is very low, “there has been some talk about former Soviet scientists [who] suddenly found themselves out of a job when the Soviet Union fell apart [and] were sort of on the market for hire. How much of this is real and how much of this is hearsay is hard to know.” The CDC also acknowledges that “credible concern exists that the virus was made into a weapon by some countries and that terrorists may have obtained it.”
Even if the overall probability of an attack remains low, the use of smallpox as a weapon presents a particularly frightening set of circumstances, in part because of the natural severity of the virus as it was seen in the past. According to the CDC, the most common type of smallpox—variola major—historically had a 30% death rate and left many survivors disfigured. Transmitted mainly by face-to-face contact, smallpox featured a seven- to seventeen-day incubation period. This was followed by sores in the mouth and ultimately the formation of contagious pustules. All told, a smallpox infection could last for a month.
Therefore, as with many terrorist threats, the government must find a balance between being prepared for a potential attack and dealing with the financial and logistical costs involved in preparation. There is no treatment for smallpox (although the CDC is investigating the drug cidofovir), but large-scale vaccination both prevents the uninfected from contracting smallpox and lessens its severity in the recently infected. Of course, vaccination does not come without risk: according to the New York State Department of Health, for every 1 million people vaccinated, one or two will die, fourteen to fifty-two will experience life-threatening reactions, and about 1,000 people will experience other serious reactions. In 2002, President George W. Bush announced a program that would lead to the vaccination of military personnel and healthcare workers. However, the program was stopped because the threat of a smallpox attack was not imminent enough to outweigh the adverse reactions experienced by a small number of the workers being vaccinated.
Today, the CDC reports that it plans to create smallpox healthcare teams in the event of an attack. First, officials would quarantine anyone infected by smallpox. The teams would then employ a strategy called “ring vaccination,” in which individuals who had been in contact with smallpox patients would be vaccinated first. After that, the teams would vaccinate people who had been in contact with anyone from the first round of vaccinations. In this way, individuals would be vaccinated in “rings” moving away from those actually being treated for smallpox. Though no one would be forced to receive the vaccine, people who refused vaccination “may need to be isolated for at least 18 days to check for infection,” according to the CDC. Though the public may take comfort in the fact that there is enough smallpox vaccine for every person in the United States, there is evidence that the CDC’s plan may not be as effective as hoped. According to a New York Times article that discussed a study by Kaplan, David Kraft, and Lawrence Wein, mass vaccination would prevent many more deaths than ring vaccination would. The study assumed 1,000 people had been infected in a large city and found that ring vaccination would allow 110,000 deaths and take nearly a year to stop the epidemic, while mass vaccination (once officials were notified of an attack) would result in 560 deaths over the course of a 115-day outbreak.
In an interview, Kaplan discussed other obstacles to implementing the federal government’s plan, including the possibility of a terrorist group engineering the smallpox virus to be more transmissible. It could also be released in an area with a high concentration of illegal immigrants, who may not notify authorities about a health problem immediately. In addition, Kaplan warned against automatically regarding a smallpox attack as a one-time event. In that case, biosensors, which test the air for biological weapons and are spread around the country, would be helpful in quickly locating areas that had been attacked.
For the meantime, however, most sources concede that although a smallpox attack could be disastrous, the probability of one actually occurring is very low. Because of this, Kaplan and other experts advocate focusing on gathering intelligence and stopping specific threats. As for the future of smallpox attacks and bioterrorism in general, Kaplan stated, “I don’t see it becoming either less or more important. I think it’s out there as a very remote but high consequence threat.”