Low-Level HIV Viremia Confers Near-Zero Risk for Sexual Transmission

Although it is clear that persons living with HIV and undetectable viral load do not transmit HIV to their partners (“Undetectable=Untransmittable” [U=U]), less is known about transmission risk when viral load is detectable but below the threshold for virologic failure (i.e., 1000 copies/mL). In this systematic review, the authors included eight studies (four cohort studies, three randomized controlled trials, and one cross-sectional study) that focused on sexual transmission in the setting of low-level viremia. The analysis included 7762 serodiscordant couples (primarily male-female).

Three studies showed no sexual transmission when the partner living with HIV had a viral load below 200 copies/mL. In one study, no instances of sexual transm…