Study Could Reduce Anthrax Shots, Decrease Side Effects
By Karen Fleming-Michael
Special to American Forces Press Service
FORT DETRICK, Md, Nov. 1, 2002 A study to decrease the required number of Anthrax shots and its accompanied side effects is being conducted at the Walter Reed Army Institute of Research in Maryland.
"We want to use our stores of vaccine wisely and we want to immunize people effectively and minimize side effects," said Col. Janiine Babcock, principal investigator for the study. The study's goals are twofold.
The first is proving the anthrax vaccine, manufactured by BioPort Corp in Lansing, Mich., is still effective when subjects are given fewer doses than the normal regimen of six shots delivered at one, two and four weeks and then at six, 12 and 18 months, with annual boosters.
"The (current vaccination) schedule is extremely cumbersome," Babcock said. "It is expensive to implement, and it is very difficult to support from a vaccine production and logistical point of view."
Decreasing the number of doses will also increase patient acceptance, she said. "If you have your choice between six shots and three, we'd all pick three."
The second goal is to change the way the shots are given, which should reduce the side effects of redness, tenderness, swelling and discomfort sometimes associated with the vaccine. Currently, the shot is given subcutaneously, which means the needle is inserted just between the skin and muscle.
"When you give vaccines (like the anthrax vaccine) subcutaneously, they work very well stimulating the immune system in a very powerful way, but they can cause more local side effects," Babcock said.
Serious reactions remain statistically rare. However, of the 2,120,594 doses given to 528,015 service members, 11 people reacted severe enough to result in hospitalizations that were "certainly or probably caused" by the vaccine, according to a May 2002 Anthrax Vaccine Expert Committee report.
By the mid-1970s, most vaccines were given by intramuscular injections because they produce fewer side effects and they are easier to administer. The anthrax vaccine, which was developed in the 1950s and 1960s and licensed in 1970, remained a subcutaneous injection because only a few hundred people, mostly veterinarians, received it each year, and no one approached the Food and Drug Administration about changing it.
"When we now vaccinate hundreds of thousands of people, we want to use it as well as we can," said Col. Alan Magill, deputy division director for Communicable Diseases and Immunology and also a study associate investigator.
The study hopes to show that intramuscular shots are the best way to deliver the vaccine, which will make it more tolerable for service members who must receive it.
The clinical study is based on preliminary results Dr. Phil Pittman found in a study conducted at the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md., from 1996 to 1998.
"In his study (of 173 subjects), the people who got the fewer doses intramuscularly had levels of antibodies that were not inferior (to the subcutaneous injections) and the reactions were much fewer," Babcock said.
The study, funded by Congress, has three parts: Part A is a human study, Part B is a primate study and Part C is a basic science study.
WRAIR is participating in Part A, which involves testing the change from subcutaneous to intramuscular injection and decreasing the number of doses. Part B will test the changed regimens against an aerosol challenge in primates to show whether they are protected from getting anthrax.
Part C will go a long way in helping develop new generations of the anthrax vaccine. Researchers will examine blood samples from people and primates taken at the same times, such as before a dose and after a dose, to find the key things in the immune system that predict protection.
"We want to find out what the best marker of protection is. Once we've found that, researchers can use that to help develop the next generation of vaccines and validate them," Babcock said. The study will last for 43 months. Of the five centers in the United States hosting the trials-- Baylor College of Medicine in Houston, Texas; Emory University in Atlanta, Ga.; University of Alabama at Birmingham and the Mayo Clinic in Minnesota -- WRAIR is the only military site.
Three hundred of the study's 1,560 subjects will participate at WRAIR. None will be active-duty military because service members need to receive the shots under the current FDA license.
"We believe that optimal use of the anthrax vaccine is important for the daily lives of our soldiers, and we wanted to be part of that solution, not five years down the road reading a report on it," Babcock said.
(Karen Fleming-Michael is a staff writer for the Standard, the Ft. Detrick biweekly newspaper.)