Nearly zero risk of sexually transmitting HIV when viral loads are less than 1000 copies per mL

Reference

Broyles LN, Luo R, Boeras D, Vojnov L. The risk of sexual transmission of HIV in individuals with low-level HIV viraemia: a systematic review. Lancet 2023;402(10400):464-471. 

Synopsis

These authors searched multiple databases, conference proceedings, and registries to identify studies that evaluated sexual transmission of human immunodeficiency virus (HIV) among serodiscordant couples. They ultimately included 8 studies with 7762 serodiscordant couples from 25 different countries. The authors report that, overall, the studies were at low risk of bias. Because the studies were quite different (1 cross-sectional study, 1 case-control study, 3 cohort studies, 1 analysis of the placebo arm in a randomized trial, and 2 randomized trials), the authors chose not to pool the data. In 3 studies, when the viral load was less than 200 copies per mL, there was no sexual transmission of HIV. Four studies identified 323 cases of transmission, none occurred in partners who were considered to be adequately suppressed with antiretroviral therapy. In 2 of the studies, 81% and 92% of the transmissions occurred when the viral loads exceeded 10,000 copies per mL. Finally, the authors identified only 2 cases of transmission when the viral load was less than 1000 copies per mL.