Vaccines for preventing anthrax.

BACKGROUND: Anthrax is an acute bacterial skin disease which may be fatal. Three anthrax vaccines are commercially available but their comparative effectiveness and safety is not clear. OBJECTIVES: The objective of this review was to assess the effects of human anthrax vaccines in healthy adults and children. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register, Medline, Embase and the reference lists of articles. We handsearched the journal Vaccine and contacted researchers in the field. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing anthrax vaccines with placebo, vaccines for other diseases or no intervention. DATA COLLECTION AND ANALYSIS: Trial quality assessment and data extraction was conducted independently by the six authors. MAIN RESULTS: Two trials involving 16,052 people were included. Both trials had methodological limitations. Compared to placebo, vaccination was associated with a reduced risk of contracting anthrax (relative risk 0.16, 95% confidence interval 0.07 to 0.35). Compared to placebo, the killed vaccine was associated with a higher incidence and severity of adverse effects (odds ratio 5.15, 95% confidence interval 2.28 to 11.61). Just over 5% of participants in the vaccine group reported adverse effects. The effectiveness of the vaccine does not appear to be influenced by the route of inoculation. REVIEWER'S CONCLUSIONS: Killed anthrax vaccines appear to be effective in reducing the risk of contracting anthrax with a relatively low rate of adverse effects. Further research should be restricted to testing new vaccines only.