The current value of tuberculin testing and BCG vaccination in school children

We have examined the value of routine tuberculin testing and BCG vaccination in Edinburgh school children from 1970 to 1983. Over 89,000 children were observed for a mean period of 7 years, during which 77 new cases of tuberculosis were notified in Caucasians. The average annual incidence of tuberculosis in the 65,692 children receiving BCG vaccination at school was 7/10(5), significantly less than the 19/10(5) estimated in 12,987 Heaf negative children who missed BCG vaccination, and the 41/10(5) in 5,308 tuberculin positive children (P less than 0.001). The efficacy of BCG vaccination in this study exceeded 60%. The 5,308 tuberculin positive children were offered chest radiographs with an initial yield (new cases of tuberculosis detected/radiographs taken) of 1/555 for Heaf grade II children, 1/75 for grade III, and 1/25 for grade IV (P less than 0.001). During the period of this study approximately 700 BCG vaccinations were necessary to prevent one new case of tuberculosis and this represents considerably greater benefit than in England and Wales during the same period. There may be a case for continuing the schools' BCG programme in Scotland for a number of years longer than in England and Wales. A national BCG survey for Scotland would be valuable.