Messaging about HIV Transmission Risk When Viral Load Is Undetectable: Reactions and Perceived Accuracy among US Sexual Minority Men

Scientific evidence indicates that HIV viral suppression to an undetectable level eliminates sexual transmission risk ("Undetectable=Untransmittable” or “U=U”). However, U=U messaging has been met with skepticism among sexual minority men (SMM) and others. In this survey-based experiment, we manipulated messaging about HIV risk and examined reactions and perceived message accuracy among US SMM. SMM living with HIV (n=106) and HIV-negative/status-unknown SMM (n=351) participated in an online survey (2019-2020). Participants were randomly assigned to one of three messaging conditions, which varied by level of HIV sexual transmission risk associated with an undetectable viral load (No Risk [U=U]/Low Risk/Control). Participants reported reactions, message accuracy, and reasons for perceiving inaccuracy. We coded open-response data (reactions and reasons) into conceptual categories (e.g., “Enthusiasm”). We compared reactions, accuracy ratings, and reasons by condition and serostatus. In the No Risk Condition, common reactions were Enthusiasm (40.0%), Skepticism/Disagreement (20.0%), and Agreement (19.4%), reactions common to comparison conditions. A higher percentage of HIV-negative/status-unknown participants (24.1%) expressed Skepticism/Disagreement in the No Risk Condition compared with other conditions (3.2%-9.7%). Participants living with HIV were more likely than HIV-negative/status-unknown participants to perceive all messages as accurate. In the No Risk Condition, common reasons for perceiving inaccuracy were Risk Misstated (46.1%), Oversimplified/Caveats Needed (17.1%), and Personal Unfamiliarity/Uncertainty (14.5%), reasons common to comparison conditions. Across conditions, 10.3% of participants attributed message inaccuracy to misdefinition of undetectable. Most SMM reacted favorably to U=U messaging. However, many—especially HIV-negative/status-unknown SMM—expressed skepticism. Interventions are needed to enhance U=U understanding and acceptance.