Hepatitis C reinfection following successful direct-acting antiviral therapy among patients attending a multidisciplinary treatment centre for people who use drugs in Zurich, Switzerland

Background: On-going risk-exposure followed by reinfection may jeopardize hepatitis C elimination efforts among people who use drugs. We estimated the HCV reinfection incidence in patients who successfully completed HCV therapy and attended a low-threshold access centre for comprehensive addiction medicine. Methods: Retrospective chart review was undertaken, in a convenience sample of patients with opioid/cocaine use disorders who achieved sustained viral response (SVR) after direct-acting antiviral (DAA) therapy in Zurich, Switzerland between April 2015 and July 2019 (n = 153). HCV reinfection incidence in patients with and without on-going drug use was calculated. Results: 79% of the patients were in opioid agonist treatment, and 19% were being managed for other medical or psychiatric conditions. 58% used drugs after SVR, of whom 49% injected. The follow-up period totalled 346 (median 2.1) person-years (py). Overall HCV reinfection incidence was 1.2 (CI-95: 0.3 to 3.0) per 100 py and 1.6 (0.2 to 5.8) in patients with drug use after SVR. Conclusion: The risk of HCV reinfection after DAA therapy in persons who use drugs can be low if, after SVR, patients remain in care in a well developed comprehensive harm reduction setting.