Risk of disability for US army personnel vaccinated against anthrax, 1998-2005.

To evaluate the potential for long-term or delayed onset health effects, we extended a previous cohort study of disability separation from the army associated with vaccination against anthrax. Analyses included stratified Cox proportional hazards and multiple logistic regression models. Forty-one percent of 1,001,546 soldiers received at least one anthrax vaccination; 5.21% were evaluated for disability. No consistent patterns or statistically significant differences in risk of disability evaluation, disability determination, or reason for disability were associated with anthrax vaccination. There was a dose-related trend in risk of disability for soldiers with 2 years' service, limited to those entering service in 2000 or later. Divergent patterns in risk suggest confounding by temporal or occupational risks of disability.