Viral load suppression trends among young people with perinatally-acquired HIV on long-term antiretroviral therapy in Ndwedwe Local Municipality, South Africa.

Young people with perinatally acquired HIV (YPpHIV) in rural South Africa face persistent challenges in achieving and sustaining viral load (VL) suppression despite long-term antiretroviral therapy (ART). We conducted a retrospective cohort study using routinely collected TIER.Net data from eight primary healthcare facilities in Ndwedwe Local Municipality, KwaZulu-Natal, including YPpHIV aged 10-35 years who initiated ART before 2015 and had at least 10 years of treatment. Longitudinal VL trends were summarised across ART-duration categories (0-3, 4-6, 7-10, 11-15, and ≥16 years), and repeated VL outcomes were assessed using Gaussian and binary generalised estimating equations accounting for within-participant correlation. Suppression was evaluated at <50, <400 and <1000 copies/mL, with adjusted odds ratios reported for each threshold. The cohort comprised 542 participants (mean age 16.4 years; 53.0% female). Viral suppression improved with increasing ART duration, while adjusted mean log10 VL declined progressively; at ≥16 years, the odds of VL <50 suppression were more than sixfold higher than at 0-3 years. Clinic of care was associated with virological outcomes, whereas sex and age at ART initiation were not consistently associated. Strengthening long-term adherence support, maintaining effective ART, and addressing clinic-level variation may support durable viral suppression in YPpHIV.