What Is Anthrax

Anthrax is a potentially fatal disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax bacteria are naturally occurring, with spores found in soil throughout the world. These spores can withstand extreme heat, cold, ultraviolet (UV) light, gamma radiation, and drought for long periods without nutrients or air.

Infection occurs when the spores enter the body through a cut, abrasion, or open sore or by ingestion or inhalation of the spores. Once inside the body, anthrax spores germinate into bacteria that then multiply and secrete three proteins: protective antigen (PA), lethal factor (LF), and edema factor (EF). Individually, these proteins are non-toxic, but they can become lethal if allowed to combine and interact on and within the cells of the exposed human or animal.

Mechanism of Anthrax

Inhalational anthrax is the most lethal form of anthrax, with fatality rates reaching up to 90%, depending on whether aggressive treatment is provided soon enough after exposure. Because of their size — between 2 and 6 microns in diameter — anthrax spores can be easily aerosolized and occupy the lower respiratory mucosa in humans when inhaled. Accordingly, aerosolized anthrax spores are the form most likely to be used in an anthrax bioterrorism attack.

A vaccine is available for pre- and post-exposure protection against anthrax.

Click here to learn more about BioThrax® (Anthrax Vaccine Adsorbed)

The safety and efficacy of BioThrax have not been established in pediatric or geriatric populations.

BioThrax may not protect all individuals vaccinated, particularly patients with impaired immune responses due to congenital or acquired immunodeficiency or immunosuppressive therapy. Individuals are not considered protected until they have completed the three-dose primary vaccination series.

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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.