Dear Dr. Friedman:

Because anthrax is the most lethal biological warfare threat today, and because a fully licensed vaccine is available, DoD is evaluating an immunization initiative to protect U.S. forces. While the package insert for this vaccine is nonspecific as to the route of exposure, DoD has long interpreted the scope of the license to include inhalation exposure, including that which would occur in a biological warfare context. Please advise whether the FDA has any objection to our interpretation of the scope of the licensure for the anthrax vaccine. In advance of this letter, I have spoken with Dr. Kathryn Zoon, Director, Center for Biologics Evaluation and Research, on this matter.