Study Title: Evaluating HIV viral rebound among persons on suppressive antiretroviral treatment in the era of “Undetectable equals Untransmittable (U=U)”

Background Studies have demonstrated that persons with HIV (PWH) maintaining viral suppression do not transmit HIV to HIV-negative partners through condomless sex, leading to the "Undetectable = Untransmittable (U = U)" prevention campaign. However, few studies have examined the durability of suppression in the era of U = U. Methods This retrospective cohort study was conducted in Providence, Rhode Island. PWH aged ≥18 years with documented viral suppression (defined as at least 1 viral load [VL] <200 copies/mL and no VL ≥200 copies/mL) in 2015 were included in the baseline cohort. Primary outcomes were viral suppression, viral rebound (at least 1 VL ≥200 copies/mL), or gap in VL monitoring assessed annually from 2016 to 2019. Those with viral rebound were assessed for resuppression within 6 months. Demographic and clinical characteristics associated with viral rebound or gaps in VL monitoring were investigated by bivariate analysis and logistic regression. Results A total of 1242 patients with viral suppression were included in the baseline cohort. In each follow-up year, 85%-90% maintained viral suppression, 2%-5% experienced viral rebound, and 8%-10% had a gap in VL monitoring. Among those with viral rebound, approximately one-half were suppressed again within 6 months. In the logistic regression models, retention in care was significantly associated with viral suppression, while younger age, black race, high school or equivalent education, non-men who have sex with men, and history of incarceration were significantly associated with viral rebound. Conclusions In the U = U era, most patients with viral suppression who are retained in care are likely to maintain viral suppression over time. Some patients require additional support for regular VL monitoring.