Lessons learned from implementing a large-scale contact investigation and TB preventive treatment project in India.

BACKGROUND: TB preventive treatment (TPT) is central to reducing TB incidence among high-risk populations. This paper presents learnings from a large-scale TPT implementation under a Global Fund-supported project in India. METHODS: The project targeted household contacts (HHCs) of people with pulmonary TB (PTB) across 208 districts in 23 states. Data on symptom-based screening, TPT initiation, adherence, and completion were analysed to inform scale-up strategies. RESULTS: Of 3,097,831 HHCs identified from 851,974 people with PTB, 91% were symptom-screened, and among those screened 28% underwent chest X-ray and 54% initiated TPT, with an 84% completion rate. Integration with active case finding, portable digital chest X-rays, and short-course regimens (3HP) improved coverage. Decentralised service delivery through Health and Wellness Centres and engagement of community health workers enhanced treatment access and follow-up. Teleconsultations, digital tracking, and incentive mechanisms supported adherence. Challenges included early discontinuation due to adverse drug reactions, regional diagnostic disparities, and limited private sector engagement. CONCLUSION: Large-scale TPT delivery is feasible in high-burden settings when integrated with routine health system platforms and community-based approaches. Key operational insights included chest X-ray screening, and scale-up of shorter regimens, supporting India's TB elimination goals.