Anthrax Vaccine Expected to Protect Troops from Illness, Death
By Staff Sgt. Kathleen T. Rhem, USA
American Forces Press Service
WASHINGTON, Jul. 21, 2000 Recent media reports that large numbers of American troops would become incapacitated after an anthrax attack are not true, DoD medical experts insist.
In tests on monkeys in 1991 and 1999, 18 of 20 vaccinated animals survived a lethal dose of inhaled anthrax, and none of the remaining animals became seriously ill, said Dr. (Col.) Arthur Friedlander, the senior military scientist for the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md.
"These animals did not appear to be sick," he said. "Their activity appeared to be normal." It's sometimes difficult to interpret animal behavior, Friedlander said, and researchers have more careful notes on the animals' reactions in the more recent test. But none of the test animals were lying down and incapacitated in either test, he stressed.
More significantly, the animals involved in the two tests each received two doses of vaccine. U.S. service members are receiving the Food and Drug Administration-approved regimen of six shots, Friedlander said. So the animals stayed healthy even on one-third the dosage of vaccine.
The animals were also given "hundreds of times a lethal dose" of anthrax. "These numbers are clearly numbers that one would see in various battlefield scenarios," he said. "It's been estimated this range is certainly what you would see or more than what you would see on the battlefield."
Friedlander acknowledged the vaccine's effectiveness hasn't been tested extensively on humans, but he explained why that's nearly impossible. He said biological warfare agents present "an unusual circumstance" in the way vaccinations are evaluated.
"There's not enough [naturally occurring circumstances of this] disease in the world to do the kind of study you can do with a measles vaccine or a chicken pox vaccine," Friedlander said. "Furthermore, you can't do challenge studies with volunteers because this is not the flu; this is not a cough and fever; this is a fatal disease."
While extrapolation of data from monkey studies to humans isn't foolproof, it's the best method available to researchers in determining the effectiveness of this vaccine, "unless a cloud appears over Washington, D.C., and the people in the Pentagon survive and others don't," he said. "Of course that's a doomsday scenario, and we hope that never happens. But, barring something like that, animal studies are the best we have."
The only way to determine the vaccine's effectiveness specifically in humans is by measuring antibodies in the blood, but this method is in its infancy for the anthrax vaccine.
"We know that everybody responds to this vaccine by making an immune response," Friedlander said. "There are ongoing studies to determine how predictive those antibody levels are of immunity." DoD is conducting these studies in coordination with the Centers for Disease Control and Prevention, in Atlanta.
What researchers do know about anthrax is that nearly 100 percent of people who receive a lethal dose and aren't treated with massive doses of antibiotics before symptoms develop will die. Immediate administration of antibiotics may save lives after exposure, Friedlander said, but the percentages are unclear because there's no way to test this on humans.
The main problem with relying on antibiotics to deal with an anthrax threat is there's no surefire way to determine exposure. DoD experts have said repeatedly that anthrax is odorless, colorless and tasteless, and modern detection systems aren't reliable enough. It's nearly impossible to diagnose early in the disease's course because early symptoms resemble the cold or flu. Experts say that by the time you can identify the disease it's usually too late to save the patient's life.
Another problem with using antibiotics is that anthrax "in the spore form can remain latent or dormant for long periods of time ... even in the human body," Friedlander said.
Individuals are protected while they're on antibiotics, but there's still a chance they can become ill after they stop taking the drugs. "We know this from experimental studies. This has occurred," he said.
This evidence was strong enough to convince defense officials the U.S. military should implement a vaccination program to protect against anthrax and not rely on antibiotics to protect service members after exposure.
Friedlander seemed surprised by recent controversy over the possibility of troops getting sick after an anthrax attack.
"We know that this was weaponized by Iraq; they have it ready to go. And we know we have a vaccine that's been licensed for use since 1970. Could some people become ill? We don't know that for sure," he said. "Do we have reason to think they'll become incapacitated? No, we do not. On the contrary, animal studies suggest that will not be the case."
"We have a fatal disease and an acknowledged threat. The alternative to taking the vaccine is death. For us that's a no- brainer."