Effectiveness of bacillus Calmette Guerin (BCG) vaccination against extra-pulmonary tuberculosis: a case-control study.

A hospital-based pair-matched case-control study was carried out at Govt. Medical College Hospital, Nagpur, to estimate the effectiveness of BCG vaccination against extra-pulmonary tuberculosis. The study included 125 cases of extra-pulmonary tuberculosis in the age group of 0-30 years and 375 tuberculosis free control. Each case was pair matched against three separate controls for age, sex and socioeconomic status. The protective effectiveness and prevented fraction were higher for the subjects in the age group of 0-10 years, males and subjects from middle and upper strata of socio-economic class but it was statistically nonsignificant. The overall vaccine effectiveness and prevented fraction was estimated to be 80.86 (72.68-86.60) and 53.20 (41.97-63.73) per cent respectively. Results of this study thus indicated that BCG vaccination was highly effective against extra-pulmonary tuberculosis and played a significant role in its prevention in this population.