Mathematical modeling of hepatitis c virus (HCV) prevention among people who inject drugs: A review of the literature and insights for elimination strategies

Abstract

In 2016, the World Health Organization issued global elimination targets for hepatitis C virus (HCV), including an 80% reduction in HCV incidence by 2030. The vast majority of new HCV infections occur among people who inject drugs (PWID), and as such elimination strategies require particular focus on this population. As governments urgently require guidance on how to achieve elimination among PWID, mathematical modeling can provide critical information on the level and targeting of intervention are required. In this paper we review the epidemic modeling literature on HCV transmission and prevention among PWID, highlight main differences in mathematical formulation, and discuss key insights provided by these models in terms of achieving WHO elimination targets among PWID. Overall, the vast majority of modeling studies utilized a deterministic compartmental susceptible-infected-susceptible structure, with select studies utilizing individual-based network transmission models. In general, these studies found that harm reduction alone is unlikely to achieve elimination targets among PWID. However, modeling indicates elimination is achievable in a wide variety of epidemic settings with harm reduction scale-up combined with modest levels of HCV treatment for PWID. Unfortunately, current levels of testing and treatment are generally insufficient to achieve elimination in most settings, and require further scale-up. Additionally, network-based treatment strategies as well as prison-based treatment and harm reduction provision could provide important additional population benefits. Overall, epidemic modeling has and continues to play a critical role in informing HCV elimination strategies worldwide.

Keywords: Epidemic modeling; Hepatitis c virus; Infectious disease; People who inject drugs; Public health; Transmission.

Figure 1.. Example schematic for a simple HCV transmission epidemic model among PWID.

Figure 2.. Levels of combination prevention required to achieve WHO elimination targets (80% reduction in incidence by 2030) among PWID populations in various settings (20/40/60% chronic HCV among PWID).

Results show the coverage of HCV DAA therapy (y axis) combined with different levels of harm reduction (white and gray boxes) required to reduce HCV incidence by 80% from 2018–2030 across three settings with varied baseline chronic HCV among PWID (20%/40%/60%). Updated simulations from Martin based on a previously published model[19].