Panel: Smallpox vaccine not for everyone

ATLANTA, Georgia (CNN) -- A government advisory panel decided Thursday not to reinstate widespread smallpox vaccination, yet the equivalent of the population of a small town will be eligible for inoculation against the disease.

An estimated 10,000 to 15,000 people could receive the vaccine, agreed the Centers for Disease Control's Advisory Committee for Immunization Practices. Included in the group are those who would be on the front lines in treating smallpox should there ever be an outbreak -- doctors, nurses and possibly even hospital housekeeping staff.

The decision came after the panel heard Wednesday from scientists who argued against reinstating mass vaccinations for the general public.

Routine smallpox vaccinations were discontinued in the United States in 1972, and the disease was eradicated globally in 1980. But after the September 11 terrorist attacks, government officials began stockpiling vaccine and looking at U.S. vaccination policy because of the possible use of the virus in a biological weapon.

Dr. Walter Ornstein, director of the Centers for Disease Control and Prevention's National Immunization Program, said diphtheria, measles and mumps are much more contagious than smallpox, which is not easily transmitted airborne -- and smallpox's obvious symptoms would key doctors into its presence quickly. The smallpox vaccine is effective even if given several days after a person is exposed to the disease.

Ornstein cited data from cases of smallpox in Europe between 1955 and 1971 that showed 55 percent of those who acquired the disease did so at a hospital and another 20 percent were infected by a family member.

"Most transmission is predictable," he said. "About 93 percent can be predicted."

How big a threat?

But Dr. Donald A. Henderson, director of the Department of Health and Human Services' Office of Public Health Preparedness, told the panel that it is possible to dry the smallpox virus and add stabilizers so it can persist a long time in the air like anthrax, making its spread less predictable.

EXTRA INFORMATION The facts about smallpox

And Dr. Don Millar, an environmental hazards expert who has worked with the CDC in the past, argued that the federal government needs to pick a course of action and stick with it.

"Whether the smallpox vaccine should be made available hinges on one question: How big is the threat of a bioterrorism attack with smallpox?" he said. "The government is behaving as though the threat is real."

He continued, "If there's no threat, they should quit demanding expenditures. If there is a threat, then we need a good reason why we have not made the vaccine available."

The current policy of withholding the vaccine "makes no sense," Millar said.

"We have no shortage," he said. "If we withhold the vaccine, the decision must be defended."

But Dr. Thomas Mack, a professor of preventative medicine with 40 years experience in population outbreaks, said that the degree of threat must also be weighed against the hazards of the vaccine itself. A key deterrent to reinstating mass vaccinations, he said, is the short supply of vaccinia immunoglobin (VIG) -- used to treat patients who develop complications related to the vaccine.

The European data indicated that patients who developed complications and were treated with VIG had a survival rate near 30 percent, while those who did not receive the treatment had virtually no chance of survival.

"This is the single most dangerous live virus vaccine we have," Mack said. "We don't need vaccination. We need ... personnel" to track reports of the disease and react quickly.

Weighing the risks

Mass vaccinations carry with them other risks, as well, particularly to those with compromised immune systems, such as HIV patients, cancer patients, organ transplant patients and those with certain skin conditions.

In a government-funded study earlier this year, one-third of the 680 healthy young volunteers getting the vaccine had a reaction serious enough to interfere with school or work.

However, smallpox itself is even more lethal. Before it was eradicated in 1980, about one-third of those affected died and others were left severely scarred or blind.

But, several of the scientists said, mass communication is much more effective now than it was as recently as 30 years ago, making it more unlikely that an outbreak of smallpox could take hold.

"Look, if this happened today, we'd have CNN, who'd be screaming the names of the persons who were exposed and if you'd been exposed to that person you'd go out and get the vaccine," said Dr. J. Michael Lane, a former CDC employee now working with the center on smallpox issues.

Health officials predict that by the end of 2002, there will be enough vaccine available to inoculate every American.

In addition to Americans younger than 30 who were never vaccinated, immunity against smallpox may be waning in Americans older than 30 who were vaccinated -- and they may need to be revaccinated.

One study found that of 621 microbiologists in Maryland who received smallpox revaccination between 1994 and 2001 as a precautionary measure, only 6 percent were still immune from their previous vaccinations. Another government-funded study is under way at St. Louis University to determine how well smallpox immunity has endured.

The CDC already has a policy to use what is known as "ring vaccination" in the unlikely event smallpox is ever released. Under this policy, those infected and their close contacts would be vaccinated and quarantined to reduce spread of the disease. The vaccine can stop the virus in its tracks if given within three to five days of exposure.

About 59 percent of Americans surveyed by the Harvard School of Public Health and the Robert Wood Johnson Foundation said they would get vaccinated as a precaution if it was offered to them.