Can BCG-vaccinated children be included in tuberculin surveys to estimate the annual risk of tuberculous infection in India?

SETTING: Selected villages in three defined zones of India.
OBJECTIVES: To compare the estimated prevalence of tuberculous infection among children with and without bacille Calmette-Guérin (BCG) scar. STUDY
DESIGN: During a nationwide tuberculin survey, 1-9-year-old children were tuberculin tested using 1TU-PPD RT23 with Tween 80.
RESULTS: In the 5-9 year age group, subgroups of tuberculous infected children could be seen as distinct humps among those with or without BCG scar, but not in those aged 1-4 years. In children aged 1-4 years, the estimated prevalence of infection was respectively 3.5%, 3.8% and 3.6% among children without BCG scar, and 4.8%, 4.7% and 4.5% among children with BCG scar in the western, northern and eastern zones. In those aged 5-9 years, the estimated prevalence was respectively 10.4%, 11.0% and 9.1% among children without BCG scar and 11%, 11.9% and 8.7% among children with BCG scar in the three zones. Thus, in children aged 1-4 years, the estimated prevalence among those with BCG scar was considerably higher than in those without BCG scar. This difference was small in those aged 5-9 years.
CONCLUSION: Tuberculin surveys may be conducted irrespective of BCG scar status among children aged 5-9 years, when BCG vaccination is given using Danish 1331 strain during infancy under the Expanded Program of Immunization.