Scar size and effectiveness of Bacillus Calmette Guerin (BCG) vaccination in the prevention of tuberculosis and leprosy: a case-control study.

BACKGROUND: The study was undertaken to estimate the effectiveness of BCG vaccination in relation to scar size in the prevention of tuberculosis and leprosy. METHODS: The present study was designed as hospital-based pair-matched case-control study and was carried out at Government Medical College Hospital, Nagpur, Maharashtra, India. It included 877 cases of tuberculosis and 292 cases of leprosy (diagnosed by WHO criteria), born onwards 1962. Each case was pair-matched with one control for age, sex and socio-economic status. BCG vaccination status was assessed by examination for the presence of BCG scar, immunisation records if available and information from subjects/parents of children. Subjects uncertain about BCG vaccination were not included. The diameter of the BCG scar was measured both across and along the arm in millimeters using a plastic ruler. The average was then calculated. RESULTS: A significant protective association between BCG vaccination and tuberculosis (OR=0.38, 95% CI 0.31-0.47) and leprosy (OR = 0.38, 95% CI 0.26-0.55) was observed. The overall vaccine effectiveness (VE) was 62% (95% CI 53-69) against tuberculosis and 62% (95% CI 45- against leprosy. Vaccine effectiveness against tuberculosis and leprosy was non-significantly greater in the group who had BCG scar size < or =5 mm as compared to subjects who had BCG scar size > 5 mm. Thus there was no clear association between BCG scar size and its effectiveness. CONCLUSION: The current study did not identify any significant association between BCG scar size and its effectiveness against tuberculosis or leprosy.

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.