BCG test reactions were studied in 1095 non-tuberculous children from 6 months to 5 years of age, who had received BCG vaccination in the newborn period, in order to find out the diagnostic value of the BCG test in previously BCG vaccinated children. Previous BCG vaccination has an effect on the BCG test reaction in the form of an accelerated BCG reaction. Although the degree of reaction decreases with time, 51.4% of children still showed a strongly accelerated BCG reaction 4 1/2-5 years after BCG vaccination. It is concluded that the BCG test cannot be used as a diagnostic test for tuberculosis in children under 5 years of age who have had previous BCG vaccination.
