The Association Between Different Levels of Suppressed Viral Load and the Risk of Sexual Transmission of HIV Among Serodiscordant Couples on Antiretroviral Therapy: A Systematic Review.

The risk of sexual transmission of HIV in serodiscordant couples when the partner living with HIV (PLHIV) uses antiretroviral therapy (ART) and maintains a suppressed viral load (VL) (< 200 copies/mL) is estimated at 0.00 transmissions per 100 person-years (95% CI 0.00-0.10). A recent review reported an almost zero transmission risk for VL < 1000 copies/mL but lacked quantitative risk estimates. This systematic review aimed to quantify transmission risk across VL levels. A literature search (November 2023, updated January 2025) identified 152 studies, with 9 included in the analysis. Seven possible transmissions occurred when the PLHIV had a VL of < 1000 copies/mL at the last measurement before the estimated time of transmission. However, VL at the exact time of transmission was unknown and VL > 1000 copies/mL cannot be excluded. This review suggests sexual transmission is very rare with recent VL < 1000 copies/mL however, future research is required to establish precise risk estimates.PROSPERO Number: CRD42023476946.