Testing for Recent HIV Infections: A Conceptual Review

Accurate HIV incidence estimation is essential for monitoring epidemic dynamics and guiding prevention strategies. Recency assays-laboratory-based or point-of-care tests that distinguish recent from long-standing HIV infection-have made cross-sectional incidence estimation increasingly feasible. This review synthesizes the evolution, validation, applications, limitations, and future directions of HIV recency assays, from early detuned assays to modern genomic approaches. We conducted a narrative synthesis of foundational methodological papers, validation studies, global guidance documents, and programmatic evaluations, including UNAIDS/WHO technical guidance and CEPHIA assay performance assessments. Recency assays have evolved through four major generations: detuned EIAs (STARHS), avidity-based assays, rapid point-of-care recency tests, and genomic incidence assays. Their performance is governed by two core metrics-mean duration of recent infection (MDRI) and false-recent rate (FRR)-which vary by subtype, ART exposure, host factors, and assay platform. Recency assays are now used in national surveys, routine HIV testing services, key-population surveillance, and outbreak detection. However, limitations include biological variability, ART-related misclassification, ethical concerns, and operational challenges. In conclusion, recency assays are powerful but imperfect tools. Their future lies in improved assay design, integration with prevention programs and trials, real-time surveillance systems, and convergence with genomic and program data. Ethical safeguards and community engagement remain essential as HIV recency testing becomes more embedded in public health practice.