Effectiveness of bacillus Calmette-Guerin (BCG) vaccination in the prevention of leprosy; a case-finding control study in Nagpur, India.

A hospital-based, pair-matched, casecontrol study was carried out at Government Medical College Hospital in Nagpur in central India to estimate the effectiveness of BCG vaccination in the prevention of leprosy. The study included 314 incidence cases of leprosy [diagnosed by World Health Organization (WHO) criteria] below the age of 32 years. Each case was pair matched with one control for age, sex and socioeconomic status. Controls were selected from subjects attending this hospital for conditions other than tuberculosis and leprosy. A significant protective association between BCG and leprosy was observed (OR 0.29, 95% CI 0.21-0.41). The vaccine effectiveness (VE) was estimated to be 71% (95% CI 59-79). The BCG effectiveness against multibacillary and paucibacillary leprosy was 79% (95% CI 60-89) and 67% (95% CI 45-78), respectively. It was more effective during the first decade of life (VE 74%; 95% CI 38-90), among females (VE 82%; 95% CI 64-90), and in the lower socioeconomic strata (VE 75%; 95% CI 32-92). The prevented fraction was calculated to be 51% (95% CI 38-62). In conclusion, this study has identified a beneficial role of BCG vaccination in the prevention of leprosy in central India.