Effect of BCG vaccine on tuberculin skin tests in 1-6-year-old children.

Abstract

Bacillus Calmette Guerin (BCG) vaccination used in the prevention of tuberculosis may cause problems in interpreting the tuberculin skin test (TST), which is commonly used in the diagnosis of infection. A limited number of studies have been undertaken to investigate how length of time after BCG vaccination affects TST results. TST induration values of unvaccinated children were compared with those of children vaccinated once in order to determine the changes in TST responses after BCG vaccination. Mantoux TSTs were administered to 1145 children aged 1-6 y and induration was measured at 72 h. BCG scar status and average TST induration diameters were identified for each age group. Average TST induration in vaccinated children is significantly higher than that in unvaccinated children, and in the vaccinated group there is no statistically significant difference between induration values in the different age groups. BCG vaccination at the age of 0-2 mo affects TST for a long period and this condition does not change until 6 y of age.