FDA approves shortened anthrax-vaccine course

Dec 22, 2008 (CIDRAP News) – The US Food and Drug Administration (FDA) recently approved a new version of BioThrax—the nation's only licensed anthrax vaccine—that requires fewer doses and changes the injection route.

Emergent BioSolutions, maker of BioThrax, said in a Dec 19 press release that the FDA's approval of the company's supplemental biologics license application for its anthrax vaccine adsorbed (AVA) allows a new schedule for the vaccine: five intramuscular (IM) doses compared with the previous regimen of six subcutaneous doses.

The vaccine is required for US military members who are deployed to the Middle East, but some have objected to the vaccine because of side effects.

The FDA's approval is based on early findings from a large multicenter trial that was initiated by the US Centers for Disease Control and Prevention (CDC) in 2002, according to the statement from Emergent. The goal of the study is to evaluate if as few as three doses of the vaccine administered over 6 months with booster doses up to 3 years apart will offer sufficient protection.

In October, researchers published their interim findings on the new BioThrax schedule in the Journal of the American Medical Association. Investigators reported that the subjects who received three or four IM, doses over 6 months had similar antibody responses to those who received four subcutaneous doses over 6 months. The volunteers who received four IM doses had fewer injection-site reactions than those who received four subcutaneous doses.

The report said the subcutaneous injection route might make the vaccine more tolerable and that reducing the number of doses in the AVA schedule could help conserve the vaccine supply.

According to the new schedule, the vaccine is administered at 0, 1, 6, 12, and 18 months. The previous course involved the same schedule, plus a dose at 2 weeks. The company recommends annual booster doses with the new dosing, the same as for the previous schedule.

Daniel Abdun-Nabi, Emergent's chief operating officer and president, said in the statement that the FDA's approval is an important milestone in the company's mission to advance the usefulness of BioThrax. "We are pleased that the US government shares our commitment to enhancing this critical countermeasure. The CDC is to be applauded for their hard work and diligence throughout this important effort," he said.

After the CDC completes more analysis of the study data in 2009, the company may seek FDA clearance to further shorten the vaccine course, if the strategy is supported by the data, Emergent said in its press release.

Since 1998, federal officials have ordered 32 million doses of BioThrax, and nearly 7.9 million doses have been administered to more than 2 million military members, the company said.

See also:

Dec 19 Emergent BioSolutions press release

Oct 6 CIDRAP News story "Trial offers hope for shortening anthrax-shot series"

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