The rate of hepatitis C reinfection in Canadians coinfected with HIV and its implications for national elimination.

BACKGROUND

The World Health Organisation (WHO) has set targets for the rate of new infections as a way to measure progress towards the elimination of hepatitis C virus (HCV) as a public health threat. As more people are successfully treated for HCV, a higher proportion of new infections will be reinfections. We consider whether the reinfection rate has changed since the interferon era and what we can infer about national elimination efforts from the current reinfection rate.

METHODS

The Canadian Coinfection Cohort is representative of HIV HCV coinfected people in clinical care. We selected cohort participants successfully treated for a primary HCV infection either in the interferon era or in the era of direct acting antivirals (DAAs). Selected participants were followed from 12 weeks after completing a successful treatment until the end of 2019 or until their last measured HCV RNA. We estimated the reinfection rate in each treatment era, overall and in participant subgroups, using proportional hazard models appropriate for interval censored data.

RESULTS

Among 814 successfully treated participants with additional HCV RNA measurements, there were 62 reinfections. The overall reinfection rate was 2.6 (95% confidence interval, CI, 1.2-4.1) /100 person years (PY) in the interferon era and 3.4 (95% CI 2.5-4.4) /100 PY in the DAA era. The rate in those reporting injection drug use (IDU) was much higher: 4.7 (95% CI 1.4-7.9) /100 PY and 7.6 (95% CI 5.3-10) /100 PY in the interferon and DAA eras respectively.

CONCLUSION

The overall reinfection rate in our cohort is now above the WHO target set for new infections in people who inject drugs. The reinfection rate in those reporting IDU has increased since the interferon era. This suggests Canada is not on track to achieve HCV elimination by 2030.