Martinez L, Cords O, Horsburgh CR, et al. - Given the exposure of tens of millions of children to Mycobacterium tuberculosis globally every year, researchers sought to estimate the risk of developing tuberculosis in exposed children and understand the effectiveness of contact investigations and preventive therapy. For this systematic review and meta-analysis, search was restricted to cohort studies published between Jan 1, 1998, and April 6, 2018, in MEDLINE, Web of Science, BIOSIS, and Embase electronic databases. Authors of all eligible studies were requested for individual-participant data and a prespecified list of variables. The final analysis was done on study groups from 46 cohort studies in 34 countries—29 (63%) prospective studies and 17 (37%) retrospective. At baseline, evaluation was performed of 137,647 tuberculosis-exposed children; of these, 130,512 children were followed for 429,538 person-years. During follow up, diagnoses of 1,299 prevalent and 999 incident tuberculosis cases were made. Observations here suggested a very high risk of developing tuberculosis among exposed infants and young children. Occurrence of most cases was reported within weeks of contact investigation initiation; prophylaxis might not preventable this. Among all exposed children, the effectiveness of preventive therapy was 63%, and among those with a positive result for tuberculosis infection, the effectiveness was 91%. Findings here emphasize the requirement for alternative strategies for prevention, such as earlier start of preventive therapy through rapid diagnosis of adult cases or community-wide screening strategies.