Use of BCG vaccine in shelters for the homeless. A decision analysis.

As a result of many interacting variables, including crowded shelters and limited access to health care, homeless persons are at high risk for tuberculosis. Using traditional approaches, control of tuberculosis in this population has been difficult. Decision analysis was used to investigate the cost-effectiveness of BCG (bacillus Calmette-Guérin) vaccination in persons attending homeless shelters. This vaccination was cost-effective over a wide range of assumptions. Using conservative assumptions, a vaccine that was at least 40 percent effective would result in a net cost savings. If the efficacy of the vaccine were 50 percent, $4,000 would be saved, 12 life-years gained, and 23 cases of active tuberculosis prevented for every 1,000 persons vaccinated. Further study of the BCG vaccine in homeless persons and other populations at risk is warranted.