A new study, paid for by the Centers for Disease Control and Prevention, will involve more than 1,500 volunteers and will test whether the anthrax vaccine is more effective when injected into muscle or when injected under the skin, which is the current practice. The study will also consider which method has the least amount of side effects and will determine the least amount of vaccinations needed for protection against the disease. Currently, the vaccine is administered in six doses over 18 months. The study will be conducted at five medical centers around the United States: Emory University in Atlanta, Walter Reed Army Medical Center in Washington, Baylor College of Medicine in Texas, the Mayo Clinic in Minnesota, and the University of Alabama-Birmingham.