The trouble with vaccines to fight bioterrorism
By Phyllis Maguire
After last fall's anthrax attacks, talk about treating and preventing illnesses caused by bioterrorism agents took on new urgency. While vaccines to prevent diseases like anthrax or smallpox may seem like an obvious line of defense, available drugs are not currently viable options.
At an Annual Session presentation on vaccines, Gregory A. Poland, FACP, explained that vaccines for both diseases are problematic, either because of their administration or their side effects. Dr. Poland is Chair of the Adult Immunization Initiative, the College's program to improve immunization rates among adults.
Anthrax. In vaccinating people against anthrax, Dr. Poland said, public health officials would have to overcome a rigorous administration schedule in which patients receive six doses over an 18-month period. After the initial dose of vaccine is given, he said, it must be repeated after two and four weeks, then after six, 12 and 18 months.
While the military has been inoculating some of its forces, a civilian population would not be as compliant. "The anthrax vaccine is not really feasible for a civilian population," explained Dr. Poland, who is also professor of medicine with the Mayo Vaccine Research Group and Mayo Clinic and Foundation in Rochester, Minn.
Another barrier to using the anthrax vaccine, he said, is fear. Since the Gulf War, Dr. Poland explained, small but vocal groups have opposed the vaccine. While some question the vaccine's efficacy, others have claimed that it actually caused many of the symptoms of Gulf War Syndrome.
Dr. Poland defended both the vaccine's safety and efficacy, adding that part of the confusion stems from misunderstanding about the vaccine itself. Most civilians—including many physicians—had never heard of an anthrax vaccine before the early 1990s. "Many think this is an experimental vaccine that came out of the Gulf War," he said.
In reality, 70,000 doses of the vaccine were administered before the Gulf War, he explained. Between 1991 and 2001, Dr. Poland added, nearly 2 million doses were administered. He said that the vaccine had a clean record from more than 2 million doses administered over 30 years.
Recently, he said, the Institute of Medicine released a report concluding that the anthrax vaccine is both safe and effective. While the vaccine does produce side effects in some patients, he said, they were similar to those produced by other vaccines.
Smallpox. Because the smallpox vaccine so successfully wiped out the naturally occurring virus, all countries have stopped giving the vaccine on a widespread scale.
The United Stated stopped global smallpox vaccination in the early 1970s, and production of the vaccine was halted in the 1980s. In 1991, the World Health Organization destroyed 200 million doses of its smallpox vaccine because of storage costs.
While public health experts believe that smallpox has been eradicated as a naturally occurring virus, stores of the virus still exist in research facilities. If unleashed, the disease could be devastating. Dr. Poland said that it is untreatable; roughly one-third of unvaccinated people who get it die.
One obvious option—resuming mass vaccinations for smallpox—carries significant risks. While side effects range from fever to encephalitis, the smallpox vaccine also kills roughly one to two patients among every million first-time recipients. Because only about half of the U.S. population has been vaccinated against smallpox, Dr. Poland said, returning to global smallpox vaccination with the current vaccine would kill approximately 300 people.
"Because of the risks," he explained, "it would be very difficult in the absence of a documented case to actually administer this vaccine."
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