The anthrax vaccine: no new tricks for an old dog

The original license for production of the anthrax vaccine, Anthrax Vaccine Adsorbed (AVA), was issued in 1970. Since that time, over 8 million AVA immunizations have been administered to 2+ million individuals. In 2002, the National Academy of Sciences, Institute of Medicine, reviewed the safety and efficacy of AVA. They concluded that the vaccine is acceptably safe and effective in protecting humans against anthrax. The vaccine should protect people against all known strains of anthrax bacteria, as well as against any strains that might be created by potential terrorists or others. Although the Institute of Medicine concluded that AVA was reasonably safe, they noted that it is fairly common for people to experience local reactions (e.g., redness and swelling at the injection site) and for a smaller number to experience systemic reactions such as fever and malaise, within hours or days of vaccination. Results of animal studies done previously and subsequent to this report are generally in agreement. For instance, AVA vaccination increases the level of anthrax anti-protective antigen IgG (anti-PA IgG), which is thought to be one possible correlate of protection (although absolute protective concentrations have not been identified in humans). Anthrax lethal factor neutralization has also been identified as possibly being an important additional correlate of immunity. Future vaccine research efforts include developing a recombinant anthrax vaccine and anthrax monoclonal antibodies to block the anthrax toxin(s). It is projected that the next-generation vaccine will elicit a markedly increased anti-anthrax immune response within a shorter time period and consequently, will enable the easier inoculations of individuals working within high-risk areas.