Anthrax Vaccine Issues
What do we really know about safety?

By Meryl Nass, MD

DECEMBER 21, 2001 - Responding to recent anthrax events, CDC has offered anthrax vaccination to people who were exposed to large doses of anthrax spores, and who are completing 60 days of antibiotics. However, there exist no human efficacy studies for this vaccine, and the data regarding safety are confusing.

No vaccine trials have been published, although one review of unpublished studies - in the Journal of the American Medical Association - reported a high degree of safety. Yet the Institute of Medicine subsequently emphasized the lack of available data for both efficacy and long-term safety.

Do data exist that might shed light on vaccine safety? During the past three years, six studies in the US, UK and Canada have begun to paint an outline of what the problems might be. They examined both US and UK anthrax vaccines, which are similar: each is a killed vaccine enriched in protective antigen (a toxin protein), and each contains an aluminum adjuvant, a catalyst which helps boost the immune response.

Some of the studies specifically inquired about anthrax vaccine, while others asked about the group of vaccines used for Gulf War deployments. Each study relied on the respondents' memory, although one published in The Lancet asked whether subjects used their vaccination record to complete the questionnaire. This study found a relationship between receiving anthrax vaccine and developing Gulf War Syndrome. The Canadian Goss-Gilroy study, published only on the Department of National Defense website, found that anthrax vaccination was related to developing chronic fatigue, a cardinal symptom of Gulf War Syndrome. A US Veterans Administration study, presented in 2001 but unpublished, found that Gulf War veterans who believed they received anthrax vaccine were twice as likely to complain of dozens of symptoms, as those who believed they had not.

One American study published in the American Journal of Epidemiology and one British study, published in Occupational and Environmental Medicine, asked whether veterans received vaccines for Gulf deployment, but not specifically about anthrax. Both studies found that receiving these vaccines was related to developing Gulf War Syndrome.

The final study, published in an army journal, evaluated a cohort of 98 British soldiers who volunteered to receive anthrax vaccine in 1998. Adverse reactions were experienced by 63% of the vaccinees, of which half were systemic. Twenty-eight percent of recipients could not lift or drive for at least 48 hours. Although initially 4 doses over 6 months are required, only 29% of the original vaccinees chose to complete the four doses of the vaccine series.

What do these studies tell us? Overall, killed anthrax vaccines cause notable initial reactions. Furthermore, a vague constellation of persisting symptoms, consistent with Gulf War Syndrome, probably results from vaccination in a measurable minority of recipients.

Therefore, a retrospective analysis of the 500,000 recent US vaccine recipients is urgently needed, before new vaccinations begin. There have been more than enough human guinea pigs injected.

Those recently exposed to anthrax, who have received 100% effective protection with antibiotics, can continue this prophylaxis a bit longer, or watch closely for any signs of infection and receive immediate treatment if this occurs.

Recommended Reading
Friedlander AM et al. Anthrax vaccine: Evidence for safety and efficacy against inhalational anthrax. JAMA 282; 22: 2104-6.

Institute of Medicine Committee on Health Effects Associated with Exposures During the Gulf War. Gulf War and Health Volume I: Depleted Uranium, Pyridostigmine Bromide, Sarin, Vaccines. National Academy Press 2000, Washington , DC.

Unwin C et al. Health of UK servicemen who served in the Persian Gulf War. The Lancet 1999; 353:169-178.

Steele L. Prevalence and patterns of Gulf War Illness in Kansas veterans: Association of symptoms with characteristics of person, place and time of military service. Am J Epidemiol 2000; 152:991-1001.

Cherry N et al. Health and exposures of United Kingdom Gulf War veterans. Part II: The relation of health to exposure. Occup Environ Med 2001; 58: 299-306.

Hayes SC and World MJ. Adverse Reactions to Anthrax Immunization in a Military Field Hospital. J R Army Med Corps 2000; 146:191-5.