By Amanda Spake

The pictures flicker across the screen portraying a real-life horror show: a baby's bottom covered with red "diaper lesions," a child's upper arm eaten away by sores, faces disfigured for a lifetime. And these are not the victims of smallpox. These are victims of smallpox vaccinations.

"I was very happy to stop giving smallpox vaccinations," says Louis Cooper, president of the American Academy of Pediatrics. Cooper's slide show was part of a public forum last week at Mount Sinai Hospital in New York City, the first of four on the growing debate about vaccination and smallpox protection. The pressing post-9/11 question at the core of this debate is how the public can best be protected–with the least risk–in the unlikely event of a bioterrorist attack involving smallpox.

Inoculate or not? Vaccinations were mandatory in the United States until 1972, but the disease was eradicated worldwide in 1980. During the period of vaccinations, about 3 in 1 million people developed encephalitis, or brain inflammation, and 2 in 1 million died from vaccinations. Severe skin infections like those in Cooper's slides were more common. According to the Centers for Disease Control and Prevention, which is sponsoring the town meetings, 1 person in 10,000 who receive the vaccine will have side effects requiring a doctor's care. Until recently, there was little vaccine and no need for it. But after the anthrax scare, the government ordered some 210 million doses, and by year's end there will be enough for most Americans. (About 38 million Americans can't be vaccinated because of health risks, including those with HIV, eczema, or compromised immune systems from cancer or organ transplants.)

The National Academy of Sciences and a special advisory panel will also weigh in on the vaccination issue in the weeks ahead. The current plan calls for "surveillance and containment" of a potential outbreak. The strategy is the same as that used 25 years ago to eradicate the disease: Quarantine cases and vaccinate the "ring" of individuals who have come in contact with them. At present, scientists who handle smallpox or related viruses are the only ones routinely vaccinated, but many say that's not enough. Susan Waltman of the Greater New York Hospital Association says, "Vaccination of healthcare workers must occur pre-attack to allow the workers to stay on the job should an attack occur." A phone survey of state health officials revealed similar thinking. Likewise, a poll released last week by the Harvard School of Public Health indicates a majority of the public would get vaccinated as a precaution if the smallpox vaccine were available. If a case of smallpox were reported in their community, 81 percent would want to be vaccinated.

A basic obstacle to an informed decision is that nobody really knows just how contagious smallpox is. The model the CDC is using, derived from calculations of past outbreaks, predicts that each known case will infect 3.5 to 6 more people. But Elizabeth Halloran, a biostatistician at Emory University, is less pessimistic. She and her colleagues developed computer simulations for five infectors coming into the United States. They calculated how many they'd infect and the success of both ring and mass vaccination in stopping the outbreak. Assuming some immunity in the population, only 1.8 new cases were generated per sick person. Allowing people to voluntarily take the vaccine would increase "herd immunity" and thus make ring vaccination more effective.