Correlation of tuberculin sensitivity before and after BCG vaccination.

The frequent experience in the tropics of poor results of BCG vaccination is sometimes explained by a hypothetical interaction with "non-specific" tuberculin sensitivity. However, samples of data from five tropical countries, reported in this paper, demonstrate a slight, positive correlation between the individual tuberculin allergy before and after vaccination. A negative correlation might have been expected had the "non-specific" allergy been the cause of the poor vaccination results, and this particular hypothesis is therefore rejected.