Emory is one of five sites nationwide selected by the Centers for Disease Control and Prevention (CDC) to conduct a clinical trial of an anthrax vaccination regimen. The study, which is now enrolling volunteers, will use the anthrax vaccine licensed by the U.S. Food and Drug Administration (FDA) in 1970. The new trial is designed to test whether changing the injection method or decreasing the number of doses affects the quality of the immune response or local reactions to the vaccine.

Harry Keyserling, professor of pediatric infectious diseases, is principal investigator for the Emory study. Other sites include Baylor College of Medicine, the Mayo Clinic, the University of Alabama at Birmingham and Walter Reed Army Medical Center.

Anthrax is a disease caused by the Bacillus anthracis germ, and most often is found in cattle and sheep. Infection with anthrax bacteria may cause skin sores and intestinal or lung illness that is often serious and may be fatal. Individuals become infected with anthrax when they eat or touch animal parts that contain the bacteria, or when they eat, touch or breathe anthrax bacteria in the air or on the ground.

The last human clinical trials of the anthrax vaccine were conducted in the 1950s in goat mill workers and in the laboratory scientists who studied the disease. In 1991, under the potential threat of Iraqi biological weapons during the Gulf War, the U.S. military began vaccinating soldiers headed to the Persian Gulf. A shortage of vaccine (and an exhaustive vaccination schedule that stretched over several years) required many soldiers to complete their anthrax immunizations on the battlefield.

In 1998, after assessing the threat of biological weapons, the Department of Defense required all U.S. armed forces to receive the anthrax vaccine. More than 2 million people, mostly in the military, have been immunized since FDA approval of the vaccine in 1970. Currently the vaccine is recommended for those in the military who may be exposed to germ warfare and for scientists who work with anthrax in the laboratory.

The current FDA-approved course for the anthrax vaccine requires an initial dose followed by injections after two weeks, four weeks, six months, 12 months, 18 months, and a yearly booster thereafter. These injections are given subcutaneously (under the skin), and some vaccine recipients have experienced pain and swelling in the arm where the vaccine was given. Investigators believe this local reaction might be avoided if the vaccine were given in the muscle of the arm. In 2000, Congress asked the CDC to study the method of injection for the vaccine and the number of doses required.

Participants in the new clinical trial will be randomly placed in one of six study groups to be vaccinated over 43 months. One group will receive the licensed regimen of eight vaccinations under the skin. Another group will receive eight vaccinations of a saltwater placebo. The remaining groups will be vaccinated in the muscle rather than under the skin and will receive fewer vaccine doses.

Blood will be drawn following each vaccination to evaluate the protective immune response. No live anthrax bacteria will be used in the study; the vaccine does not contain the whole anthrax germ and cannot cause an anthrax infection.

A total of 1,560 volunteers nationwide will be enrolled in the clinical trial, and Emory will enroll approximately 200 of these volunteers. Partici-pants must be 18–61 years of age and must not have any major health problems. The study will require 25 visits over 43 months. At each visit, participants will either receive an injection, have an investigator look at the injection site, or have blood drawn. Participants will not know which study group they are in until the end of the study. All laboratory tests will be provided free, and participants will receive compensation for each visit.

“The anthrax vaccine has an excellent safety record,” Keyserling said. “We hope this new study will simplify the existing dosing and shot regimen for the vaccine and provide more data to convince an anxious public that the vaccine is safe.”

For more information, call Keyserling’s research staff at 404-727-4044.