Theme: Epidemiology & Public Health Research Year: 2022
Background: Men who have sex with men carry a high burden of hepatitis C virus (HCV) and some
inject drugs (MSM-IDU). We estimated the impact of HCV testing and treatment among MSM-IDU in
San Francisco.
Methods: We developed a dynamic HCV/HIV transmission model among MSM calibrated using data
from biobehavioural surveys and community-based health services in San Francisco, including
proportion of MSM-IDU [defined as past-year injecting; 6.0% (2017)], HCV antibody prevalence [15.5%
and 2.3% in MSM who ever and never injected, respectively (2011], HIV prevalence, self-reported
HCV/HIV diagnosis, treatment and PrEP history. DAAs were introduced in 2015. We assumed high
levels of HCV testing [79.1%-86.2% MSM ever tested (2011-2019)] and HCV treatment [65.4%
diagnosed MSM ever treated (2018)]. During 2020, HCV testing decreased by 59.1% due to the COVID19 pandemic and was assumed to gradually rebound by 2025. We modelled the decrease in chronic
HCV prevalence and HCV incidence due to current levels of treatment by 2022 and 2030.
Results: In 2015, chronic HCV prevalence and HCV incidence were estimated at 15.5% (95%CI: 9.4-
21.9) and 1.9/100 person-years (95%CI: 0.8–3.5) among MSM-IDU, respectively, and much lower
among MSM with no past-year injecting (MSM non-IDU: 3.6% (95%CI: 2.8-4.2) and 0.2/100 personyears (95%CI: 0.1–0.3)) [Figure]. With current treatment, our model estimates that chronic HCV
prevalence and HCV incidence have decreased by 68.4% (95%CI: 60.7-78.7) and 70.5% (95%CI: 62.3-
80.0) over 2015-2022 in MSM-IDU, respectively, and will decrease by 90%-92% over 2015-2030 in
both, MSM-IDU and MSM non-IDU.
Conclusion: Despite a high burden of HCV in MSM-IDU in San Francisco in 2015 and a reduction in HCV
testing due to the COVID-19 pandemic, we estimate that HCV incidence will decrease by >80% over
2015-2030, achieving WHO elimination targets. Results likely reflect San Francisco’s multilayered
efforts to increase HCV service access for marginalized populations.
Disclosure of Interest Statement: SNF has received consulting fees from Gilead Sciences outside the
conduct of the study; PV reports an unrestricted grant from Gilead Sciences, outside the conduct of
the study; MDM reports grants from Gilead Sciences, outside the conduct of the study; all other
authors have no conflicts of interest to disclose.