High rates of early HCV reinfection after DAA treatment in people with recent drug use attended at mobile harm reduction units.

Background And Aims: The World Health Organization recently called for the elimination of hepatitis C virus (HCV) and has identified people who inject drugs (PWID) as a key target population. Clinical trials analyzing currently available all-oral regimens have demonstrated a high degree of efficacy in this population, with a relatively low reinfection rate. There is an urgent need to confirm these data in a harm reduction and active consumption setting. The primary aim of this study was to evaluate the HCV reinfection rate in people with recent drug use followed at low-threshold mobile harm reduction units.

Method: We included people with recent drug use (smoked or injected heroin/cocaine in the previous 6 months) who received HCV treatment and were attended at two low-threshold mobile harm reduction units over 19 months. Sustained virologic response was assessed 12 weeks after therapy (SVR12). The incidence density of HCV reinfection was defined as the number of reinfections per 100-person years (PY) using person-time of observation and was stratified by drug consumption at initiation of HCV treatment. Cox proportional hazard regression analysis was used to assess factors associated with reinfection.

Results: During the study period, 160 people who used drugs in the past 6 months completed HCV therapy. 122 (73.9%) and 88 (53.3%) reported injecting drug use in the 6 months and 30 days prior to HCV treatment, respectively. The overall SVR12 was 68% in the ITT analysis (reinfection = failure) and 90.7% in the modified intent-to-treat analysis (considering reinfections as response and removing people who were missing SVR data). The cohort at-risk for reinfection (n = 121) included 47 (39.2%) people who initiated HCV treatment with recently reported abstinence. Reinfection was identified in 10 persons (8.3%), and the median time to reinfection was 7.2 (IQR 4.2-18) months. Total follow-up time at-risk was 101.1-PY (median 0.6 years, IQR 0.3-1.3). The overall incidence of reinfection was 9.8 per 100-PY (95% CI 4.7,18.2). The incidence of reinfection was higher amongst those who had injected drugs in the previous 6 months (16.7 [95%CI 8.0; 30.7] per 100-PY) and in the previous 30 days (18.9 [95% CI 8.1; 37.2] per 100-PY). In the adjusted analysis, only injecting drugs use in the month prior to initiation of HCV therapy was associated with reinfection (aHR 8.7, 95%CI 1.0; 73.6; p 0.04).

Conclusion: High efficacy of HCV treatment, was found in people with recent drug use attended and followed at low-threshold mobile harm reduction units. The high rate of early HCV reinfections in this setting should promote surveillance for reinfection at 7-month intervals after ending the treatment or earlier.