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CDC Updates Postexposure Anthrax Vaccination Recommendations

Kate Traynor

Today's issue of Morbidity and Mortality Weekly Report includes updated recommendations on the use of the anthrax vaccine in people who have been exposed to Bacillus anthracis spores.

Building on information gained during last fall's anthrax attacks, the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) announced that it endorses the use of a three-dose anthrax vaccine regimen administered under an investigational new drug protocol. The vaccine would be used in conjunction with antimicrobial therapy in people at risk for inhalational anthrax and would be administered after exposure to the bacterium, two weeks later, and four weeks postexposure.

ACIP recommends that antimicrobial prophylaxis, when given in conjunction with the vaccine, begin after exposure and continue until 7–14 days after the third vaccine dose is given. For anthrax-vaccine naive people who are exposed to B. anthracis and do not receive postexposure vaccination, ACIP recommends 60 days of antimicrobial therapy.

The advisory committee noted that some people may have completed part or all of the anthrax vaccination series before being exposed to the microbe. Because the effectiveness of full or partial anthrax vaccination is not known, ACIP recommends that everyone who has been partially or fully vaccinated receive at least 30 days of postexposure drug prophylaxis. Anthrax vaccination of such people should continue as described in the product's labeling, according to ACIP.

Current labeling for the U.S.-licensed anthrax vaccine, BioThrax, by BioPort Corp. of Lansing, Mich., calls for the administration of three subcutaneous doses two weeks apart, additional doses at 6, 12, and 18 months, and annual booster injections thereafter. The vaccine's licensed indication is for active immunization of people at high risk for exposure to B. anthracis spores. The labeling notes that the safety and efficacy of BioThrax for postexposure prevention of anthrax have not been established.