Adverse reactions
There have been no long-term sequelae of the known adverse events (local or systemic reactions) and no pattern of frequently reported serious adverse events for AVA.The approved FDA package insert for AVA contains the following notice: "The most common (>10%) local (injection-site) adverse reactions observed in clinical studies were tenderness, pain, erythema and arm motion limitation. The most common (>5%) systemic adverse reactions were muscle aches, fatigue and headache." Also, "Serious allergic reactions, including anaphylactic shock, have been observed during post-marketing surveillance in individuals receiving BioThrax". Drug interactions
The approved US FDA package insert for AVA contains the following notice:

Immunosuppressive therapies may diminish the immune response to BioThrax. Post-exposure vaccination
Some studies show that use of antibiotics effective against anthrax plus administration of AVA is the most beneficial approach for purposes of post-exposure prophylaxis. This practice has been endorsed by the Advisory Committee on Immunization Practices (ACIP), the Johns Hopkins Working Group on Civilian Biodefense, and the 2002 Institute of Medicine report on the vaccine. However, AVA is not licensed for post-exposure prophylaxis for inhalational anthrax or for use in a 3-dose regimen. Any such use, therefore, would be on an off-label or IND (officially experimental) basis. "... the safety and efficacy of BioThrax for post-exposure setting have not been established.". Controversy
In the United States
Although many individuals have expressed health concerns after receiving anthrax vaccine, a congressionally directed study by the Institute of Medicine (part of the National Academy of Sciences) concluded that this anthrax vaccine is as safe as other vaccines.
As with the Sterne (veterinary) anthrax vaccine strain and the similar British anthrax vaccine (known as AVP), AVA lacks the capsule plasmid pXO2 (required for full virulence) and is composed chiefly of the anthrax protective antigen (PA) with small amounts of edema factor (EF) and lethal factor (LF) that may vary from lot to lot. Other uncharacterized bacterial byproducts are also present. Whether or not the EF and LF contribute to the vaccines efficacy is not known. AVA has smaller amounts of EF and LF than AVP. Adjuvant
AVA contains aluminium hydroxide (alhydrogel) to adsorb PA as well as to serve as an adjuvant (immune enhancer). As such it is believed to stimulate humoral, but not cell-mediated, immunity. Each dose of the vaccine contains no more than 0.83 mg aluminum per 0.5 mL dose. (This is near the allowed upper limit of 0.85 mg/dose.) It also contains 0.0025% benzethonium chloride as a preservative and 0.0037% formaldehyde as a stabilizer. The mechanism of action of the adjuvant is not entirely understood. Potency/immunogenicity
Vaccination of humans with AVA induces an immune response to PA. More than 1/3 of subjects develop detectable anti-PA IgG after a single inoculation; 95% do so after a 2nd injection; and 100% after 3 doses. The peak IgG response occurs after the 4th (6 month) dose. The potency of AVA vaccine lots is routinely determined both by the survival rates of parenterally challenged guinea pigs and their anti-PA antibody titres as measured by an enzyme linked immunosorbant assay (ELISA).