Study population
To this prospective study we recruited children aged < 18 years admitted to the Children’s Hospital, Medical University of Warsaw, Poland, and Mazovian Centre for Treatment of Lung Diseases and Tuberculosis, Otwock, Warsaw Agglomeration, Poland between May 2012 and September 2015. Eligible for participation were 1) children with clinical suspicion of TB and 2) children in recent contact with pulmonary TB (PTB). Exclusion criteria included immunosuppression, previous antituberculous treatment, and TST performed within the last 18 months to minimize the risk of boosting. Ethics approval for this study was provided by the Bioethical Committee of the Medical University of Warsaw and written informed consent was obtained from the legal guardian of each participant before enrollment.