The blog of the 2009 – 2017 Presidential Commission for the Study of Bioethical Issues

What is anthrax vaccine adsorbed and what do we know about it?

Anthrax is an infection of the skin, intestinal tract, or lungs caused by exposure to spores of the bacterium, Bacillus anthracis. Although several types of antibiotics are approved by the U.S. Food and Drug Administration (FDA) to prevent and treat anthrax, such antibiotics do not provide long-term protection against the persistence of dormant spores. Data from animals suggest that combining antibiotics with anthrax vaccine adsorbed (AVA) provides better protection against anthrax disease than treating with antibiotics alone.

What is AVA?

AVA is a vaccine used to prevent anthrax disease. Currently, AVA is the only anthrax vaccine licensed by FDA.

First licensed in the United States in 1970, AVA is approved for use in persons 18 through 65 years of age who are at high risk of exposure to B. anthracis spores. The vaccine is approved for use before exposure has occurred, though FDA has authorized adminis¬tration of AVA to adults to prevent infection after exposure under certain emergency circumstances. AVA given before potential exposure to B. anthracis is administered in five doses over 18 months, followed by an annual booster.

What do we know about AVA?

Although few in the civilian population have received AVA, it has been widely distributed to members of the military. Since 1998, over 1.5 million military personnel have been vaccinated with AVA.

Evaluations of AVA indicate that its safety profile is comparable to other vaccines. Testing in both animals and human adults has revealed that the most common reactions to AVA include tenderness and redness near the injection site. Other mild reactions near the injection site—such as itching, development of a lump, and bruising—have also been reported, but they are less common. Even more rare are systemic events, such as fever, malaise, and myalgia.

The immunogenicity of AVA, that is, the ability of AVA to produce an immune response, has also been evaluated in both adult humans and animals, and data from these studies demonstrate AVA’s ability to produce a meaningful immune response to combat anthrax infection. However, although the mechanism of immunogenicity is understood, the precise level of antibody that confers protection against anthrax is unknown.

Although human challenge studies (research in which individuals are exposed to a disease or pathogen to test a drug or biologic’s ability to prevent infection) would be unethical in the case of anthrax, studies in animals suggest that AVA is effective, and that it is most effective when combined with antibiotics. Observational studies conducted when individuals are naturally exposed to B. anthracis also suggest that the vaccine is efficacious in adults. Data from a 1962 study evaluating an early anthrax vaccine (not AVA), indicated that the vaccine provided protection against the development of cutaneous anthrax disease.

What is left to learn about AVA?

Research on AVA is ongoing. The Centers for Disease Control and Prevention and the Institute of Medicine have stated that future research on AVA should include studies on long-term side effects, alternative dosing methods, and quantitative correlates of immunity in animal models.

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This is a space for the members and staff of the 2009 -2017 Presidential Commission for the Study of Bioethical Issues to communicate with the public about the work of the commission and to discuss important issues in bioethics.

As of January 15th, 2017 this blog will no longer be updated but continues to be available as an archive of the work of the 2009-2017 Presidential Commission for the Study of Bioethical Issues

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