Treat all, treat fast: time from HIV diagnosis to treatment initiation in Switzerland, 1996-2025

Abstract Background Immediate antiretroviral therapy (ART) initiation after HIV diagnosis is a clinical and public health priority. The “treat-all” strategy – ART initiation irrespective of CD4+ cell count – improves health outcomes and curtails further transmissions. Using data from the Swiss HIV Cohort Study, we assessed time from HIV diagnosis to ART initiation and associated socio-demographic and clinical characteristics to evaluate how rapidly and equitably it was adopted at a national level. Methods We analysed participants diagnosed in 1996-2025. Time from HIV diagnosis to ART initiation was assessed using Kaplan-Meier estimates, and associated characteristics were evaluated by fitting time-updated Cox proportional hazards models. Results Among 7’525 participants diagnosed between 1996 and 2025, 93.1% initiated ART. Median time to ART initiation declined steeply from 983 days (2005) to 63 days (2010), reaching 12 days by 2025; 42.2% initiated ART within one week in 2025. CD4+-based differences disappeared, with median ART initiation times falling below three weeks across all strata by 2025. Higher viral load remained associated with faster ART initiation, though absolute differences in ART timing between viral load strata were small. Participants from Africa and the Americas showed significantly lower initiation hazards than Europeans in 2017-2025, with absolute differences of at most one week by 2025. By transmission mode, people who inject drugs (PWID) consistently showed the lowest ART initiation hazard. Conclusions Universal treatment was rapidly implemented in Switzerland, with a shift towards rapid and equitable ART initiation. Residual differences for viral load, region of origin and PWID warrant continued monitoring.