Washington—The nation's only anthrax vaccine, mandatory for most military personnel since 1998, is as safe as any other vaccine and will prevent infection from inhaled spores, concludes an extensive report issued by the Institute of Medicine (IOM) early this month. However, the report committee made it clear that the vaccine should be given only to those at high risk for exposure. Last fall's anthrax attacks left some physicians in a quandary when panicked patients demanded the vaccine.
These main conclusions were darkened by the report committee's concern about the vaccine's inadequacies, including an 18-month immunization schedule, painful subcutaneous delivery, and outdated design. Manufactured by Bioport Corp, Lansing, Mich, the vaccine was developed in the 1950s at Camp Detrick (now Fort Detrick), Maryland, which at the time housed a biological weapons program.
While fears of attacks from similar weapons prompted the military to adopt the vaccine, the injections were originally meant to ward off anthrax from a much less sinister source—barnyard animals. In fact, the only randomized, placebo-controlled human study, which led to US Food and Drug Administration (FDA) approval in 1970, involved workers at goat-hair mills.
QUESTIONS IN THE MILITARY
Decades later, a number of concerned servicemen and servicewomen raised questions about the vaccine they were required to receive. Reports of chronic fatigue–like symptoms, memory loss, suspected links to Gulf War illness (some veterans of that war received the vaccine), and other complaints surfaced after the military's mass vaccination program began. Many refused to be vaccinated against anthrax. The fracas led Congress to direct the IOM to conduct the study, which was expedited after last fall's mail attacks.
Despite the high visibility of the vaccine's detractors, the IOM committee found no evidence of serious adverse events. The frequency and type of adverse effects fall within the range considered normal, said committee chair Brian Strom, MD, MPH. Itching and soreness at injection sites, occasional fatigue, and viruslike symptoms all resolved within a few days, according to the committee's review of the Vaccine Adverse Event Reporting System (VAERS), a joint program of the FDA and the Centers for Disease Control and Prevention to monitor all licensed vaccines.
The committee also found that despite limited data, "the available evidence to date does not confirm any long-term health risks. . . ." However, because no vaccine is 100% safe, the committee said, the Department of Defense should create systems to enhance long-term monitoring of health conditions that might be associated with any vaccine given to military personnel.
Reports of serious illnesses such as Guillain-Barré syndrome and atrial fibrillation were very rare and either unrelated to the anthrax vaccine or unclassifiable, concluded the committee. However, they also said that VAERS tends to underestimate the true number of adverse events. The system relies heavily on physician initiative to complete and return forms. Many, even those who care for military patients, simply are not aware of the process or do not bother with it, said committee member Hugh Tilson, MD, DrPH, senior advisor to the dean at the School of Public Health, University of North Carolina, Chapel Hill.
In addition, the report notes that some military vaccinees complained that they had been discouraged from reporting adverse effects: "In at least one Air Force squadron there is a perception that seeking care for symptoms of unknown origin or filing a VAERS report carries the risk of being labeled a malingerer. . . ." The committee found that the US Department of Defense had responded appropriately to the complaints.
REQUEST FOR NEW PRODUCT
All things considered, the concerns were enough to prompt the committee to make a forceful plea for an improved vaccine. Ideally, a new vaccine would not cause any severe reactions, would require two or three injections instead of six, and would prompt immunity within 30 days that lasts for at least a year. In addition, the report said, any new vaccine needs a long shelf life to ensure ample stockpiles for a worst-case biological attack.
The committee noted that natural mutations or bioengineered alterations in anthrax bacteria would not be apt to produce strains that are vaccine resistant. The vaccine acts directly on a toxin from the bacteria, which must remain unaltered for the bacteria to retain its lethal nature.
