Top 6 things to know about anthrax vaccine

November 24, 2015

FDA this week approved a new indication for BioThrax to prevent disease following suspected or confirmed exposure to Bacillus anthracis, the bacterium that causes anthrax disease.

FDA approved a new indication for BioThrax (Anthrax Vaccine Adsorbed) to prevent disease following suspected or confirmed exposure to Bacillus anthracis, the bacterium that causes anthrax disease.

“With today’s approval of BioThrax, we now have a vaccine that can be used, together with antibiotic treatment, to prevent disease after exposure to anthrax spores,” said Karen Midthun, MD, director of FDA’s Center for Biologics Evaluation and Research.

Related:Treatment for inhalational anthrax approved

Here are the top 6 things to know about the new vaccine:

  • The vaccine’s new use is approved for people aged 18 to 65 years in conjunction with recommended antibiotic treatment. BioThrax was initially approved by FDA in 1970 for the prevention of anthrax disease in persons at high risk of exposure.

  • Anthrax disease, especially the inhalation form, is often fatal if not promptly treated. Anthrax is considered one of the more likely agents to be used in a biological attack, primarily because its spores are very stable and easy to disperse. Although it is rare, people may contract anthrax disease through natural exposures, such as contact with infected animals or contaminated animal products.

  • BioThrax is manufactured by Emergent BioDefense Operations Lansing, based in Lansing, Mich.

  • BioThrax is the first vaccine to receive approval based on the Animal Rule, which allows animal efficacy data to be used as a basis for approval when human efficacy studies are not ethical or feasible. The ability of BioThrax to increase the probability of survival after stopping post-exposure antibiotic treatment was assessed in rabbits. Rabbits treated with both antibiotics and BioThrax had a survival rate of 70 to 100 percent, depending on the vaccine dose administered. In contrast, in 2 studies of rabbits that received only antibiotic treatment, survival rates were 44% and 23% respectively.

  • The safety and antibody responses to BioThrax in humans were evaluated in a multicenter study conducted in the United States. Subcutaneous injections were given to 200 healthy adults in three doses at zero, two, and four weeks. The majority of study participants generated antibody responses that correlated to a 70% probability of survival that was observed in animal models.

  • The observed adverse reactions were comparable with those observed when BioThrax is used for pre-exposure disease prevention. The safety profile for BioThrax is well-established, with the majority of localized adverse events reported as tenderness, pain, swelling, and redness at the injection site, as well as limited movement of the injected arm. The most common systemic adverse reactions were muscle aches, headache, and fatigue.