The New Worry: Smallpox

First, the good news: There is no reason to believe anyone has any plans to introduce smallpox into the United States. Now, the not-so-good news: There is no guarantee someone won’t use smallpox against us as a biological weapon.

Given the not-so-good news, the U.S. government has decided now might be a good time to look into vaccinating the entire nation against smallpox — a disease that was officially eradicated in 1977. It’s no small task: Health officials estimate we now have about 15 million doses of the vaccine, and there are plans afoot to purchase another 300 million. The government could also dilute existing doses just enough to inoculate everyone — without, we can only assume, compromising the immunizing threshold of the vaccine. The vaccine, drawn from active smallpox cultures, can also slow or stop the advance of the disease if administered during the first four days after exposure to the virus.

The Lowdown on Smallpox While the U.S. public now knows more about anthrax than it ever wanted to know, information about smallpox is less ubiquitous. Looking for answers, TIME.com turned to Dr. Lee Harrison, a medical epidemiologist and infectious disease specialist, also works with the Biomedical Security Institute, a joint venture of the University of Pittsburgh’s Graduate School of Public Health and Carnegie Mellon University. TIME.com: What is smallpox? Lee Harrison: Smallpox is a virus. It’s a naturally occurring disease that’s transmitted from person to person via "droplet nuclei," or saliva, somewhat analogous to chicken pox. It first evolved long, long ago and eventually became a major pathogen for humans. How does smallpox differ from anthrax? Well, with anthrax, either you’re exposed to the attack medium, or you’re not. Anthrax is very containable and very treatable. With smallpox, on the other hand, you’re dealing with a highly contagious virus that, if it were used as a bioweapon, has major potential for damage. Also keep in mind that we’re living in a very susceptible society; we stopped vaccinating people in the early 1970s. Are there different strains of smallpox? Yes. There’s one called variola minor, which has a very low death rate, and one called variola major, which has the 30 percent death rate. Bioterrorists would most likely use the variola major strain. Which countries currently have access to smallpox bacteria? The party line is that it’s at the CDC and in a lab in Russia, but it’s certainly within the realm of believability that it’s present in other labs as well. All of this is purely speculative, unfortunately.

It would be an emergency vaccination plan, designed to pick up where the government left off in 1972, when routine smallpox vaccinations fell out of favor. (Experts can’t determine the level of immunity among those vaccinated before 1972, so pretty much everyone would have to be immunized again.)

Smallpox is caused by the variola virus, and is spread from one person to another via infected saliva droplets. A person exposed to the virus might not show any symptoms for 12 days before developing a high fever, fatigue, headache and generalized back pain. Two or three days later, a characteristic rash develops over the face, arms and legs; the rash begins as flat lesions which fill with pus, then scab over and fall off in three or four weeks. Roughly 30 percent of smallpox patients eventually die.

History is scarred by the scourge of smallpox. The first recorded epidemic of the disease dates back to 1350 BC, and since then, hundreds of millions of people — old, young, rich and poor — have died or been blinded or disfigured by the smallpox virus. This story was supposed to have a happy ending: On May 8, 1980, nearly 200 years after Edward Jenner first inoculated a patient against smallpox, the 33rd Assembly of the World Health Organization (WHO) formally announced the eradication of the disease. Sixteen years later, the World Health Assembly recommended that the last smallpox stocks (thought to be held at the Centers for Disease Control in Atlanta and the Institute for Viral Preparations in Moscow or the Russian State Center for Research on Virology and Biotechnology, in Koltsovo) be destroyed. The original deadline was 1999, but was pushed back to 2002.

Meanwhile, an unknown number of independent laboratories have developed technologies to produce smallpox; at least two of those labs are in the former Soviet Union, and others may be spearheaded by their former countrymen, wooed away by various rogue nations.