Is San Diego California on Track to Reach HCV Elimination? A Modeling Analysis of Combination Prevention Strategies.

In 2020, the in the county of San Diego (COSD) was launched, a private-public joint endeavor between the COSD and the American Liver Foundation. We use epidemic modeling to assess whether the COSD is on track to reach its elimination targets (80% reduction in incidence, 65% reduction in hepatitis C virus (HCV)-related mortality by 2030 compared to 2015) and what intervention scale-up may be required. We adapted a previously developed dynamic, deterministic model of HCV transmission and disease progression among adults in the COSD, stratified by risk, age, gender, and human immunodeficiency virus (HIV) status. The model is calibrated to detailed historical epidemiological data on HCV burden, treatment, and mortality in the COSD. We project HCV infections and mortality under status quo HCV treatment (65%/year among people coinfected with HCV and HIV, 0-5%/year among others) and determine what treatment scale-up among those without HIV is required to achieve HCV elimination, with or without concomitant reductions in injection transmission risk from 2024 onward. We project an increase in new HCV infections in the COSD to 2213 [95% C.I.: 1069-3763] in 2030, a mean 91% relative increase between 2015 and 2030. HCV-related deaths are expected to decrease to 246 [95% C.I.: 180-295] in 2030, a mean relative decrease of 14% compared to 2015. The incidence elimination target could be achieved through increasing HCV treatment among those without HIV to a mean of 60%/year, similar to the level achieved among people coinfected with HCV and HIV. Combination interventions reduce the treatment needed; if injecting risk is reduced by 25%, then treating 48%/year could achieve elimination. The COSD is likely not on track to reach the incidence or mortality targets, but achieving the incidence target is possible if treatment rates overall are scaled-up to rates that have been achieved among people coinfected with HCV and HIV. Elimination is achievable but requires committed funding and expansion of comprehensive testing, linkage, and treatment programs alongside harm reduction initiatives.