HCV elimination among people who inject drugs. Modelling pre- and post–WHO elimination era

Abstract

BackgroundElimination of hepatitis C virus (HCV) among people who inject drugs (PWID) is a costly investment, so strategies should not only focus on eliminating the disease, but also on preventing disease resurgence. The aims of this study are to compute the minimum necessary antiviral therapies to achieve elimination with and without the additional expansion of harm reduction (HR) programs and to examine the sustainability of HCV elimination after 2030 if treatment is discontinued.MethodWe considered two types of epidemic (with low (30%) and high (50%) proportion of PWID who engage in sharing equipment (sharers)) within three baseline chronic HCV (CHC) prevalence settings (30%, 45% and 60%), assuming a baseline HR coverage of 40%. We define sustainable elimination strategies, those that could maintain eliminations results for a decade (2031–2040), in the absence of additional treatment.ResultsThe model shows that the optimum elimination strategy is dependent on risk sharing behavior of the examined population. The necessary annual treatment coverage to achieve HCV elimination under 45% baseline CHC prevalence, without the simultaneous expansion of HR programs, ranges between 4.7–5.1%. Similarly, under 60% baseline CHC prevalence the needed treatment coverage varies from 9.0–10.5%. Increasing HR coverage from 40% to 75%, reduces the required treatment coverage by 6.5–9.8% and 11.0–15.0% under 45% or 60% CHC prevalence, respectively. In settings with ≤45% baseline CHC prevalence, expanding HR to 75% could prevent the disease from rebounding after elimination, irrespective of the type of the epidemic. In high chronic HCV prevalence, counseling interventions to reduce sharing are also needed to maintain the HCV incident cases in low levels.ConclusionsHarm reduction strategies have a vital role in HCV elimination strategy, as they reduce the required number of treatments to eliminate HCV and they provide sustainability after the elimination. The above underlines that HCV elimination strategies should be built upon the existing HR services, and argue for HR expansion in countries without services.

Hepatitis C Reinfection in People Who Inject Drugs in Resource-Limited Countries: A Systematic Review and Analysis

“…Based on our systematic review, we also suggest that certain factors may influence the measured reinfection rates seen among PWID in upper and lower middle-income countries. Past epidemiological studies have shown that higher background HCV prevalence is associated with a higher risk of reinfection rates among people actively engaged in high-risk injection behavior (e.g., sharing needles or equipment) [ 28 ]. Modeling studies have applied this understanding and generally agree that “treat all” mandates are highly cost-effective if the background HCV prevalence in the source population is below 50% [ 28 , 29 ].…”

“…Past epidemiological studies have shown that higher background HCV prevalence is associated with a higher risk of reinfection rates among people actively engaged in high-risk injection behavior (e.g., sharing needles or equipment) [ 28 ]. Modeling studies have applied this understanding and generally agree that “treat all” mandates are highly cost-effective if the background HCV prevalence in the source population is below 50% [ 28 , 29 ]. Among studies in our review, however, background prevalence did not appear to have a significant impact on reinfection rates.…”

A hepatitis C outbreak preceded the HIV outbreak among persons who inject drugs in Athens, Greece: Insights from a mathematical modelling study

“…A previous discrete‐time, stochastic, individual‐based model of HCV transmission among PWID was used . In short, the model follows transitions concerning HCV infection between three mutually exclusive compartments of PWID: (a) susceptible people including those who either have never been HCV‐infected, have cleared infection or have had successful treatment; and (b) HCV‐infected.…”

“…After infection, PWID have a probability of clearing the disease spontaneously and are then at risk of re‐infection; to be conservative, we assumed that the risk of re‐infection was equal to the initial infection rate; those who do not clear the infection progress to the chronically infected stage. Further details about the description of the model are available in the appendix or elsewhere …”

Network‐based recruitment of people who inject drugs for hepatitis C testing and linkage to care

“…Recent data from the DAA era suggest that less than 20% of HCV‐infected PWID in different global settings have ever received HCV treatment 17‐19 . To achieve HCV elimination goals, HCV treatment uptake among PWID must increase 20 . Patient, provider and system level barriers have been extensively detailed in previous research and have been linked to low treatment uptake among PWID 21‐25 …”