Anthrax Vaccine

Safety and Efficacy Issues Gao ID: T-NSIAD-00-48 October 12, 1999

Since the Defense Department began vaccinating its 2.4 million solders and reservists in 1998, concerns have been raised about the safety and efficacy of the military's anthrax vaccine. The Food and Drug Administration discovered problems during its inspection of the facility that produces the vaccine, and some ailing Gulf War veterans believe that their unexplained illnesses may have been caused by anthrax vaccinations received during the war. This testimony discusses (1) the need for a six-shot regimen and annual booster shots, (2) the long- and short-term safety of the vaccine, (3) the efficacy of the vaccine, and (4) the extent to which problems FDA found in the vaccine production facility in Michigan could compromise the safety, efficacy, and quality of the vaccine. GAO also discusses the effects of the vaccine on children and pregnant or lactating women.

GAO noted that: (1) no studies have been done to determine the optimum number of doses of the anthrax vaccine; (2) although annual boosters are given, the need for a six-shot regimen and annual booster shots have not been evaluated; (3) the long-term safety of the licensed vaccine has not been studied; (4) however, the Department of Defense (DOD) is designing studies to examine the vaccine's long-term effects; (5) data on the prevalence and duration of short-term reactions to the vaccine are limited but suggest that women experience a higher rate of adverse reactions than do men; (6) FDA's system for collecting data on adverse events associated with the vaccine, which DOD uses, relies on vaccine recipients or their health care providers to report adverse events; (7) studies have shown that such systems may not accurately reflect the incidence of events due to underreporting; (8) however, data from two recent DOD efforts to identify the prevalence of adverse events associated with anthrax vaccine show that a higher proportion of women reported both local and systemic reactions to the vaccine than their male counterparts; (9) in addition, more than twice the proportion of women reported that they missed one or more duty shifts after their vaccinations than did males; (10) a study on the efficacy of the earlier vaccine concluded that it provided protection to humans against anthrax penetrating the skin but did not provide information to determine the effectiveness against inhalation anthrax; (11) in the 1980's, DOD began testing the efficacy of the licensed vaccine in animals, focusing on its protection against inhalation anthrax; (12) the studies showed that the vaccine protected some animals against inhalation anthrax; (13) however, the level of protection varied for different species and the results cannot be extrapolated to humans; (14) DOD recognizes that correlating the results of animal studies to humans is necessary and told GAO that it is planning research in this area; (15) DOD also plans to develop a second generation anthrax vaccine and, as part of this effort, will need to address whether strains of deliberately engineered or naturally occurring anthrax can overcome the protective immunity of such a vaccine; and (16) FDA's inspections of the vaccine production facility in 1997 and 1998 found a number of deficiencies.

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