Antigen-based skin tests in community-wide active case finding for TB.

<sec><title>BACKGROUND</title>In 2022, Mycobacterium tuberculosis antigen-based skin tests (TBSTs) were added to global recommendations for diagnosing TB infection (TBI). TBSTs have higher specificity than tuberculin skin tests (TSTs), particularly in Bacillus Calmette-Guérin (BCG)-vaccinated populations. We report results from community-wide TB active case finding (ACF) using TBSTs in remote, high-incidence communities.</sec><sec><title>METHODS</title>From May to June 2024, TBSTs were implemented in community-wide ACF for TB in the Mortlock and Northwest Islands of the Federated States of Micronesia. Home interviews and TBSTs were conducted, with follow-up at mobile clinics. If indicated, chest radiography and sputum collection were performed to evaluate for TB disease. Treatment for TBI or TB disease was initiated upon diagnosis. Programmatic data were analysed to compare TBST positivity rates with a matched TST-tested population from 2023.</sec><sec><title>RESULTS</title>1,354 participants completed ACF screening; 186 (13.7%) had a positive TBST result. Of these, 163 were diagnosed with TBI and 23 with TB disease. No adverse events were reported. TBST positivity was 0.65 times that of a propensity-matched TST-tested population.</sec><sec><title>CONCLUSION</title>TBST was both feasible and safe for community-wide ACF in remote settings. Lower TBST positivity may correlate with improved test specificity, indicative of fewer false positives in this BCG-vaccinated population.</sec>.