Window Prophylaxis for Pediatric Tuberculosis Prevention Trial

The goal of this cluster-randomized controlled trial is to evaluate the effectiveness of tuberculosis preventive treatment (TPT) administered during the "window period" to prevent new Mycobacterium tuberculosis infections in children and adolescents. The main question it aims to answer is: Can immediate TPT reduce the incidence of IGRA conversions in children and adolescents who are household contacts of a newly diagnosed pulmonary tuberculosis patient? Researchers will compare the incidence of new tuberculosis infections-measured by IGRA conversion at 12 weeks-between participants who receive immediate TPT while still uninfected (baseline IGRA-negative) and those who receive standard care, in which TPT is not offered to IGRA-negative contacts. Participants will be: 1. Tested for M. tuberculosis infection using the Interferon-Gamma Release Assay (IGRA), specifically the QuantiFERON-TB Gold Plus, at enrollment and after 12 weeks of follow-up. 2. Take weekly isoniazid and rifapentine for 12 weeks if: 1. They are assigned to the intervention arm (regardless of baseline IGRA result), or 2. They are in the control arm and test IGRA-positive at baseline. Additionally, participants from the control arm who experience an IGRA conversion at 12 weeks (following the primary outcome assessment) will also receive TPT, as per standard of care.