How It Works

Anthrax bacteria produce three proteins known as protective antigen (PA), lethal factor (LF), and edema factor (EF). If the PA protein interacts with LF or EF on the surface of human or animal cells, the resultant toxins could be lethal to anyone who became infected with the bacteria (Figure 1).

BioThrax® (Anthrax Vaccine Adsorbed) stimulates the immune system to produce protective antibodies against PA. When PA is blocked, LF and EF are not able to interact with PA and the toxins are thereby neutralized (Figure 2).

 Mechanism of anthrax and Mechanism of BioThrax  Mechanism of anthrax and Mechanism of BioThrax
Figure 1. Mechanism of anthrax
Figure 2. Mechanism of BioThrax

Contains no whole bacteria

  • Neither live nor dead bacteria are present in the final formulation of the vaccine
  • The vaccine is a sterile product made from cell-free filtrates of cultures of a strain of anthrax bacteria not capable of causing disease

Promotes a natural immune response

  • Aluminum hydroxide is included in the vaccine as an adjuvant to increase the amount of antibodies that the body makes in response to vaccination

For more information on BioThrax, please refer to the prescribing information.

Next: Why Get Vaccinated




BioThrax is a vaccine indicated for the active immunization for the prevention of disease caused by Bacillus anthracis in persons 18 through 65 years of age. BioThrax is approved for:

  1. Pre-exposure prophylaxis of disease in persons at high risk of exposure.
  2. Post-exposure prophylaxis of disease following suspected or confirmed Bacillus anthracis exposure, when administered in conjunction with recommended antibacterial drugs.

The efficacy of BioThrax for post-exposure prophylaxis is based solely on studies in animal models of inhalational anthrax.


Severe allergic reaction (e.g. anaphylaxis) after a previous dose of BioThrax or a component of the vaccine.

Adverse Reactions

The most common (≥10%) local (injection-site) adverse reactions observed in clinical studies were tenderness, pain, erythema, edema, and arm motion limitation. The most common (≥5%) systemic adverse reactions were muscle aches, headache, and fatigue. Acute allergic reactions, including anaphylaxis, have occurred with BioThrax.

Warnings and Precautions

Vaccination with BioThrax should be avoided by individuals with a history of anaphylactic or anaphylactic-like reaction following a previous dose of BioThrax or any component of the vaccine. If BioThrax is used during pregnancy, or if the patient becomes pregnant during the immunization series, the patient should be apprised of the potential hazard to the fetus. Pregnant women should not be vaccinated unless the potential benefits of vaccination have been determined to outweigh the potential risk to the fetus. It is not known whether BioThrax is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when BioThrax is administered to a nursing woman.

BioThrax should be administered with caution to persons with a possible history of latex sensitivity since the vial stopper contains dry natural rubber.