Comparison of the prevalence of tuberculosis infection in BCG vaccinated versus nonvaccinated school age children.

OBJECTIVE To compare the prevalence of tuberculosis infection in BCG vaccinated versus non-vaccinated school age children in a tuberculosis endemic region. DESIGN Cross-sectional, case control, school based survey. SETTING Government lower primary school in Palakkad District, Kerala. METHODS Tuberculosis infection was determined by tuberculin testing in 418 school children aged 5 to 9 years, utilizing a differential outcome variable definition for BCG vaccinated and unvaccinated children, in a tuberculosis endemic area with moderate vaccination coverage. Nutritional status was calculated using weight for age and weight for height criteria. RESULTS Tuberculin positivity rate in unvaccinated children (24%) was significantly higher than in the vaccinated (9.7%) (P<0.001, RR: 2.9). Overall prevalence rate of tuberculosis infection was 15.5%. Boys had significantly higher vaccination rates than girls (P < 0.001). No association was found between tuberculin reaction size and age or nutritional status. CONCLUSIONS BCG vaccination is associated with significant protection against the acquisition of Mycobacterium tuberculosis infection in childhood. This finding highlights the importance of universal implementation of BCG vaccination in children in tuberculosis endemic regions.