Background
Eliminating HCV requires curing people and ensuring they remain free of re-infection. People who inject drugs (PWID) are particularly vulnerable to re-infection, but few re-infection estimates are available from resource-limited settings. We evaluate HCV re-infection rates among PWID treated in community-based centers in 7 Indian cities.
Methods
From 2021-2022, 3000 PWID ≥18 years with active HCV infection were enrolled in a randomized trial of HCV treatment support strategies. For all, treatment was delivered from community-based centers that provided HIV and harm reduction services including medication for opioid use disorder. 1749/2994 (58%) achieved sustained virologic response (SVR), defined as undetectable HCV RNA ≥12 weeks after end-of-treatment (EOT), and were followed semi-annually using HCV core antigen (ARCHITECT) to assess re-infection rate (number of re-infections/person-time at risk). Due to the potential for re-infection between EOT and SVR visit, we performed HCV RNA testing on EOT samples (907/1245 with detectable RNA at SVR had EOT samples). Participants with EOT HCV RNA<LLOQ and high estimated treatment adherence (> 90% medication possession) were reclassified as achieving SVR. Poisson regression was used to identify predictors of re-infection after SVR.
Results
Median age of 1749 participants who achieved SVR was 30 yrs; 98% were cisgender men, 6% reported homelessness, and 41% reported injection in the 3 months before the SVR visit. There were 232 HCV re-infections between SVR and the first semi-annual visit (500 person-years [PY]) resulting in a overall re-infection rate of 46.4 per 100 PY, ranging from 23.3 to 73.6 per 100 PY across sites. Younger age, HIV co-infection, higher injection frequency, and needle sharing were associated with higher re-infection risk after SVR (p<0.01). Among 907 EOT samples, 412 had HCV RNA<LLOQ, of which 315 had >90% adherence increasing the SVR in the overall sample from 58% to 69%. Re-infection rate between EOT and SVR was 56.9 per 100 PY. From EOT to 12-months after SVR, re-infection rates declined over time (Figure).
Conclusions
In this large trial in a resource-limited setting, comprised mostly of young actively injecting men, we observed an alarmingly high re-infection rate. Our findings suggest that in the most vulnerable, true SVR may be masked by high re-infection, even between EOT and SVR. Innovative harm reduction and treatment strategies are needed to sustain the impact of HCV treatment by minimizing re-infection.