Modelling the elimination of hepatitis C as a public health threat in Iceland: A goal attainable by 2020

Abstract

Background & aims: In Iceland a nationwide program has been launched offering direct-acting antiviral (DAA) treatment for everyone living with hepatitis C virus (HCV). We estimate (i) the time and treatment scale-up required to achieve the World Health Organization's HCV elimination target of an 80% reduction in incidence; and (ii) the ongoing frequency of HCV testing and harm reduction coverage among people who inject drugs (PWID) required to minimize the likelihood of future HCV outbreaks occurring.

Methods: We used a dynamic compartmental model of HCV transmission, liver disease progression and the HCV cascade of care, calibrated to reproduce the epidemic of HCV in Iceland. The model was stratified according to injecting drug use status, age and stage of engagement. Four scenarios were considered for the projections.

Results: The model estimated that an 80% reduction in domestic HCV incidence was achievable by 2030, 2025 or 2020 if a minimum of 55/1,000, 75/1,000 and 188/1,000 PWID were treated per year, respectively (a total of 22, 30 and 75 of the estimated 400 PWID in Iceland per year, respectively). Regardless of time frame, this required an increased number of PWID to be diagnosed to generate enough treatment demand, or a 20% scale-up of harm reduction services to complement treatment-as-prevention incidence reductions. When DAA scale-up was combined with annual antibody testing of PWID, the incidence reduction target was reached by 2024. Treatment scale-up with no other changes to current testing and harm reduction services reduced the basic reproduction number of HCV from 1.08 to 0.59, indicating that future outbreaks would be unlikely.

Conclusion: HCV elimination in Iceland is achievable by 2020 with some additional screening of PWID. Maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that outbreaks are unlikely to occur once elimination targets have been reached.

Lay summary: In Iceland, a nationwide program has been launched offering treatment for the entire population living with hepatitis C virus (HCV). A mathematical model was used to estimate the additional health system requirements to achieve the HCV elimination targets of the World Health Organization (WHO), as well as the year that this could occur. With some additional screening of people who inject drugs, Iceland could reach the WHO targets by 2020, becoming one of the first countries to achieve HCV elimination. The model estimated that once elimination targets were reached, maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that future HCV outbreaks are unlikely to occur.

Keywords: Direct-acting antiviral; Elimination; Hepatitis C virus; Iceland; Mathematical model; People who inject drugs; Testing.