Long lasting BCG protection against leprosy.

BACKGROUND: BCG vaccine protects against leprosy. OBJECTIVES: Estimate BCG protection against leprosy by age by age. METHODS: A case control study with 226 cases of leprosy and 857 controls. BCG vaccination was ascertained via examination of BCG scars. Protection is presented for three age groups. RESULTS: BCG protection against leprosy was 86% (95% CI: 77-92%) in the age group 18-29; 54% (95% CI: -37% to 85%) in the age group 30-39 and 32% (95% CI: -3% to 56%) in those aged 40 or more. CONCLUSIONS: BCG efficacy against leprosy may well last for three decades and possibly even longer. BCG vaccination must have contributed to worldwide reduction in leprosy incidence.