Three-year virological outcomes among adolescent girls and young women living with human immunodeficiency virus enrolled in vertical transmission prevention services during pregnancy and postpartum in Tanzania: A prospective cohort study

OBJECTIVES: This large cohort study examines long-term trends and predictors of viremia among pregnant and postpartum adolescent girls and young women (AGYW) living with human immunodeficiency virus (HIV) in Tanzania. METHODS: This prospective cohort study included 7703 pregnant/postpartum AGYW with at least one viral load (VL) enrolled in routine prevention of mother-to-child transmission (PMTCT) care between 2018 and 2020 across three regions in Tanzania and followed for a minimum of 36 months. Poisson generalized linear models with a log link function were used to estimate adjusted incidence rate ratios and 95% confidence intervals for detectable viremia (VL ≥50 copies/mL) by baseline exposures. RESULTS: Over three years, detectable viremia was highest among the youngest age group 15-17 years (20.4%) compared with those aged 18-19 (16.7%) and 20-24 years (12.5%). Viremia declined during pregnancy but plateaued postpartum, with >10% of participants remaining viremic. Perinatally infected AGYW (HIV diagnosis at age ≤12 years) had higher rates of viremia (28.8%) than those already receiving antiretroviral therapy (ART) (11.0%) or newly initiated on ART (15.2%) who were diagnosed after childhood. Over 25% of perinatally infected AGYW remained viremic throughout the PMTCT cycle. Second-line ART and urban residence were associated with higher risk of viremia. CONCLUSION: Persistently high viremia was observed over time among Tanzanian pregnant/postpartum AGYW with HIV, particularly adolescents and those with perinatally acquired infection. Tailored PMTCT interventions, including resistance-informed treatment and youth-friendly adherence support, are needed to improve maternal outcomes and accelerate elimination of vertical transmission.