Clinical Question

What is the risk of sexually transmitting HIV when viral loads are less than 1,000 copies per mL?

Bottom Line

Among the disparate studies, when viral load was less than 1,000 copies per mL, there was nearly no chance of sexually transmitting HIV. (Level of Evidence = 2a)

Synopsis

The authors searched multiple databases, conference proceedings, and registries to identify studies that evaluated sexual transmission of HIV among serodiscordant couples. They ultimately included eight studies with 7,762 serodiscordant couples from 25 countries. The authors report that the studies overall were at low risk of bias. Because the studies were different (one cross-sectional study, one case-control study, three cohort studies, one analysis of the placebo arm in a randomized trial, and two randomized trials), the authors chose not to pool the data. In three studies, when the viral load was less than 200 copies per mL, no sexual transmission of HIV occurred. Four studies identified 323 cases of transmission, none of which occurred in partners who were considered to be adequately suppressed with antiretroviral therapy. In two studies, 81% and 92% of the transmissions occurred when the viral loads exceeded 10,000 copies per mL. The authors identified only two cases of transmission when the viral load was less than 1,000 copies per mL.