Effectiveness of Bacillus Calmette Guerin (BCG) vaccination in the prevention of leprosy: a population-based case-control study in Raipur, India

OBJECTIVE: To estimate the effectiveness of BCG vaccination in the prevention of leprosy. METHODS: study design: Population-based pair-matched case-control study. The study was carried out in the field operation area of Regional Leprosy Training and Research Centre, Raipur, Chattisgarh, India. It included 201 cases of leprosy (diagnosed by WHO criteria), born onwards 1964. Each case was pair-matched with one neighbourhood control for age and sex. BCG vaccination status was assessed by examination for the presence of BCG scar, immunization records if available and information from subjects/parents of children. Subjects uncertain about BCG vaccination were not included. RESULTS: A marginally non-significant protective association between BCG and leprosy was observed (OR = 0.65, 95% CI 0.40-1.04). The overall vaccine effectiveness (VE) was 35%. The BCG effectiveness was lower for pauci-bacillary leprosy as compared to multibacillary leprosy. The sub-group analysis revealed that the BCG effectiveness was statistically non-significant in less than or equal to 14 years of age and females category. The overall prevented fraction of leprosy was calculated to be 20% (95% CI--1.8-41.4). CONCLUSION: The current study identified a marginally beneficial role of BCG vaccination in the prevention of leprosy in study population.