The risk of HIV and HCV transmission in Canadians living with coinfection before, during, and after the COVID pandemic: A prospective cohort study.

Objectives: The COVID-19 pandemic led to lower rates of testing for HIV and hepatitis C virus (HCV) and reduced HCV treatment uptake. It is not clear what other temporary or lasting effects the pandemic might have had in Canada on factors associated with HIV and HCV transmission.

Methods: Using data from the Canadian Coinfection Cohort, we modelled outcomes related to transmission risk over a period starting 2 years before the pandemic and ending 2 years after the pandemic. We fitted generalised additive mixed models to these outcomes, rather than assume a specific functional form for the change in an outcome over time.

Results: Our modelling suggests a slow decline in the risk of HIV and HCV transmission for those in care during the period from 2018 to 2024, unaffected by the pandemic. We see a consistent picture across multiple outcomes: declines in detectable and transmissible HIV RNA, in poor adherence to antiretroviral therapy, and in injection drug use. However, a decline in sexual activity during the pandemic was mostly transitory. At the same time, a third of participants were permanently lost to care during the pandemic. Those lost to care were more likely to be using injection drugs or Indigenous people and far more likely to still be HCV RNA positive.

Conclusion: HIV and HCV elimination efforts will need to be resourced to re-engage those at greatest risk of transmission who were lost to care during the pandemic.