Why Be Concerned About Anthrax

Inhalational anthrax is the most lethal form of anthrax disease, with fatality rates reaching up to 90%, depending on whether aggressive treatment is provided soon enough after exposure7. Because of their small size, anthrax spores can be easily aerosolized, inhaled, and enter through the lower respiratory mucosa in humans. A single breath of anthrax may contain enough spores to cause disease. Accordingly, aerosolized anthrax spores are the form most likely to be used in an anthrax bioterrorism attack.

In the fall of 2001, there were 11 cases of inhalational anthrax following the intentional spread of anthrax spores through the United States Postal Service. By the time individuals with inhalational anthrax were symptomatic, antibiotics prevented death in only 6 of 11 cases.

In a report published by World Health Organization (WHO) consultants it was estimated that in just three days following the release of 50 kg of anthrax spores along a 2-km area upwind of a city with a population of 500,000, approximately 125,000 infections would occur, with about 95,000 of these cases resulting in death8. Compared to similar scenarios of the release of other bioterrorism agents, this predicted number of deaths possible after an anthrax attack is substantially higher. It has also been predicted that an aerial release of anthrax spores along a 100-km line under ideal meteorological conditions could result in a lethality rate of 50% as far as 160 km downwind9.

7Anthrax Fact Sheet. Centers for Disease Control and Prevention.

8Report of a WHO group of consultants. Health aspects of chemical and biological weapons. Geneva: World Health Organization; 1970. p. 97-9.

9Science Applications International Corporation. Effectiveness of medical intervention against battlefield levels of Bacillus anthracis. 1993.

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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.