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Background The prevalence of syphilis is increasing among adolescents and young adults (AYAs) globally. Use of syphilis rapid diagnostic treponemal tests (RDTs) may improve test coverage and same-day treatment. This study aims to determine sensitivity and specificity of two syphilis RDTs. Methods A cross-sectional study was conducted in men who have sex with men and transgender women aged 15–24 years attending a sexual health clinic in Bangkok. Syphilis RDTs used were Determine Syphilis TP and Bioline Syphilis 3.0, using whole blood from finger pricks and venipuncture. Treponemal pallidum electrochemiluminescence assay was used as standard reference. Results From February to July 2022, 200 AYAs with a mean age 21.1 (SD2.1) years were enrolled, including 50 (25.0%) living with HIV. Prevalence of syphilis was 10.5% (95%CI 6.6–15.6), which was higher among AYAs living with HIV (22.0%) compared with AYAs unaffected by HIV (6.7%). Sensitivities of Determine Syphilis TP and Bioline Syphilis 3.0 were 85.7% (95%CI 63.7–97.0) and 66.7% (95%CI 43.0–85.4), respectively. Specificity of both RDTs was 100% (95%CI 98.0–100.0). Performance of RDTs was similar for both specimens. Conclusions Syphilis RDTs have high sensitivity and specificity in diagnosing syphilis. It should be considered for use in sexual health clinics with high syphilis prevalence to initiate treatment promptly.

Introduction: Young men who have sex with men (YMSM) and young transgender women (YTGW) in Thailand are at high HIV risk. HIV self-tests (HIVSTs) are rapidly administrable and prompt linkage to HIV treatment or prevention services. This study assesses the acceptability and feasibility of blood-based HIVST use in adolescents. Methods: A cross-sectional study was conducted among YMSM and YTGW aged 15–19 years with HIV acquisition risk. Participants completed questionnaires on the HIVST and then administered INSTI® independently, an HIVST immunoassay detecting gp41 and gp36 antibodies from finger-stick blood. Confirmatory HIV antibody tests were performed. Results: Between July and September 2020, 90 adolescents were enrolled. Mean (SD) age was 17.6 (1.1) years. Half ( N = 45) were YMSM. Forty-six (51%) were first-time HIV testers, and 32 (36%) had “ever used” HIV pre-exposure prophylaxis (PrEP). Two (2.2%, 95% CI: 0.0–5.3) tested positive, 21 (23.4%) invalid, and 67 (74.4%) negative. Invalidity causes included 17 (81%) insufficient blood, 3 (14%) buffer spillage, and 1 (5%) procedural missteps; all had negative HIV antibody tests. HIV self-test acceptability was 87.8% (95% CI: 81.0–94.5). Most (79%) preferred HIVST performance in hospital rather than at home. Conclusions: HIVSTs are acceptable in HIV at-risk adolescents. Blood-based HIVSTs should be positioned as rapid point-of-care tests with real-time linkage to HIV services.