Women's Health

The Ghost of Smallpox Past

Smallpox is one of this year's top 10 medical stories. Not bad for a disease that's been dead for a quarter of a century.

Ironically, it was only last October that the CDC celebrated the 25th anniversary of the last case of smallpox in the world. Smallpox is eradicated. It stands as one of mankind's greatest achievements.

Now we fear that one of mankind's lowest acts -- terrorism -- might resurrect what 19th-century historian Thomas Macaulay called "the most terrible of the ministers of death." We worry that Soviet Cold War-era smallpox bioweapons might find their way into the hands of terrorists. We worry that rogue states might somehow develop and distribute smallpox weapons. We worry -- and now we prepare for the worst.

"The smallpox virus still exists in laboratories, and we believe that regimes hostile to the United States may possess this dangerous virus," President Bush said on Dec. 13. "Our government has no information that a smallpox attack is imminent. Yet it is prudent to prepare for the possibility that terrorists who kill indiscriminately would use diseases as a weapon."

To this end, the U.S. already has begun an ambitious smallpox vaccination program. About a half-million military personnel not deferred for medical reasons must get vaccinated. Another half-million healthcare workers will get voluntary vaccinations. After that, another 10 million healthcare workers will be offered the vaccine. The general public eventually will be able to choose vaccination. But unless there's an attack, no mass vaccination program is planned.

What is the Real Threat?

For every million people who get the vaccine, thousands will get bad reactions and one to five people will die. As Bugs Bunny used to ask in WWII-era cartoons, is this trip really necessary?

One person dealing with some of the issues involved is Kent A. Sepkowitz, MD, director of infection control at Memorial Sloan Kettering Cancer Center and associate professor of medicine at Weill Medical College, Cornel University, New York.

"What is threat of smallpox? I have no idea," Sepkowitz tells WebMD. "That is the key piece. Nobody knows. That information is missing. We are asked to take on blind faith that there is a threat and to make a plan. It is our job to wrestle with the issues."

Samuel A. Bozzette, MD, PhD, and colleagues at RAND Health Care and the VA San Diego Healthcare System, have looked at several plausible scenarios for smallpox emergencies. They aren't writing science fiction. It's a dead-serious effort to come up with cost-benefit numbers to guide public health readiness and response.

"How likely is a smallpox bioterror attack? That is a matter for the government to judge," Bozzette tells WebMD. "The president says the risk of imminent attack is low. And from scenarios we've analyzed, the range of complexity required to actually carry out these attacks varies quite widely."

In the worst-case scenario, mass public vaccination would save about 30,000 lives. But there's a catch. We prevent those "what-if" deaths at a cost of about 500 very real deaths from vaccine complications.

"Our study shows that in order for there to be a substantial advantage for mass vaccination of the public, we would need to be facing a significant threat of a very widespread attack," Bozzette says.

The surprising conclusion: Mass smallpox vaccination, either before or after a large-scale attack, won't do much net good. The reason lies in the nature of smallpox itself.