A Case-Control Study to Evaluate the Effectiveness of Mass Neonatal BCG Vaccination among Canadian Indians.

Abstract: This paper reports a case-control study to assess the protective effect of BCG (bacille Calmette-Guerin) vaccination among Indian infants in Manitoba, Canada. A record of past BCG vaccination was found in 49 per ¢ of the tuberculosis cases, compared to 77 per ¢ of the controls, yielding a relative risk of 0.30. Stratified analysis, controlling for age, increased the relative risk to 0.39 (95% confidence interval 0.22 - 0.69). The preventive fraction was 44 per ¢. Non-differential misclassification of exposure status could have occurred; if this was adjusted for, the relative risk would be reduced. If only bacteriologically confirmed cases were analyzed, the age-adjusted relative risk was 0.27. The protective effect of BCG vaccination in the newborn among Manitoba Indians is therefore at least 60 per ¢. The implications for health policy in this population are further discussed. [ABSTRACT FROM AUTHOR]