Incidence of primary hepatitis C virus infection among people who inject drugs in Australia pre- and post-unrestricted availability of direct acting antiviral therapies

Utilising Integrated Bio-behavioural Surveillance (IBBS) to investigate declining hepatitis C antibody prevalence among people who inject drugs in the Australian Needle and Syringe Program Survey

BACKGROUND

Prevalence of hepatitis C virus (HCV) antibody (Ab) on dried blood spot (DBS) samples in the Australian Needle and Syringe Program Survey (ANSPS) decreased nationally from 57% in 2015 to 32% in 2022. We aimed to investigate potential explanations for this decline.

METHODS

Changes in DBS HCV Ab prevalence were investigated by redefining positive cases as those with those with either a positive HCV Ab test result or a self-reported history of ever having HCV treatment (modified prevalence), examining HCV Ab prevalence by birth and age cohorts, and assessing trends in key risk behaviours.

RESULTS

Overall prevalence of DBS HCV Ab declined rapidly and significantly from 57% in 2015 to 32% in 2022 (p<0.001) however modified HCV Ab prevalence remained stable over time (85% and 88% in 2015 and 2022, respectively, p=0.357). The proportion of participants with negative HCV Ab and self-reported HCV infection increased from 20% in 1995 to 40% in 2022 (p<0.001) and the proportion with negative HCV Ab and lifetime HCV treatment increased from 3% in 1999 to 67% in 2022 (p<0.001). We also observed a decreasing trend in DBS HCV Ab prevalence in all birth and age cohorts with a noticeable acceleration in the decline commensurate with the advent of HCV DAA treatment. A long-term decreasing trend was also observed for key risk behaviours (p<0.001) however the short-term trend was not significant for recent receptive syringe sharing.

CONCLUSION

The temporal decline in HCV Ab prevalence appears related to reduced sensitivity of DBS HCV Ab detection with viral clearance following treatment. Since 2016, HCV treatment uptake has increased markedly including among people who inject drugs. In this context, continuing to monitor HCV Ab prevalence by DBS testing is problematic, with a shift to surveillance of active infection the most relevant to guide policy and practice in this setting.

Incidence of primary hepatitis C infection among people who inject drugs during 2012-2020 in Athens, Greece

One of the World Health Organization's targets for the 2030 viral hepatitis elimination strategy is to reduce new hepatitis C (HCV) infections. In Athens, Greece, people who inject drugs (PWID) have a high HCV prevalence, with increasing trends since the 2000s. This analysis aims to assess primary HCV incidence among PWID during 2012-2020. Two community-based interventions were implemented in 2012-2013 and 2018-2020 with repeated sero-behavioural surveys in each period. Participants enrolled in multiple surveys were identified through linkage. To assess trends in HCV transmission, three indicators were estimated: (i) anti-HCV prevalence among 'new' injectors (those injecting ≤2 years), (ii) indirect HCV incidence among 'new' injectors, assuming infection occurred at the midpoint between initiating injection and the first positive test, and (iii) HCV incidence from repeat participants. There were 431 and 125 'new' injectors, respectively, in 2012-2013 and 2018-2020. Αnti-HCV prevalence [95% CI] declined from 53.6% [48.8%, 58.3%] in 2012-2013 to 40.0% [31.3, 49.1%] in 2018-2020 (25.4% reduction, p = .007). The indirect estimate [95% CI] of HCV incidence among 'new' injectors decreased from 56.1 [49.3, 63.8] to 39.0/100 person-years (PYs) [29.6, 51.5] (30.5% reduction, p = .020). HCV incidence [95% CI] based on seroconversions in repeat participants (16/63 in 2012-2013 and 9/55 in 2018-2020) declined from 64.6 [39.6105.4] to 13.8/100 PYs [7.2, 26.5], respectively (78.6% reduction, p < .001). Primary HCV incidence remains high among PWID in Athens. Consistent implementation of combined interventions, including high-coverage harm reduction programs and initiatives tailored to increase access to HCV treatment, is essential to sustain the declining trends documented during 2012-2020.

Hepatitis C (HCV) Reinfection and Risk Factors among Clients of a Low-Threshold Primary Healthcare Service for People Who Inject Drugs in Sydney, Australia

Hepatitis C (HCV) reinfection studies have not focused on primary healthcare services in Australia, where priority populations including people who inject drugs (PWID) typically engage in healthcare. We aimed to describe the incidence of HCV reinfection and associated risk factors in a cohort of people most at risk of reinfection in a real-world community setting. We conducted a secondary analysis of routinely collected HCV testing and treatment data from treatment episodes initiated with direct-acting antiviral (DAA) therapy between October 2015 and June 2021. The overall proportion of clients (N = 413) reinfected was 9% (N = 37), and the overall incidence rate of HCV reinfection was 9.5/100PY (95% CI: 6.3-14.3). Reinfection incidence rates varied by sub-group and were highest for Aboriginal and/or Torres Strait Islander people (20.4/100PY; 95% CI: 12.1-34.4). Among PWID (N= 321), only Aboriginality was significantly associated with reinfection (AOR: 2.73, 95% CI: 1.33-5.60, p = 0.006). High rates of HCV reinfection in populations with multiple vulnerabilities and continued drug use, especially among Aboriginal and Torres Strait Islander people, highlight the need for ongoing regular HCV testing and retreatment in order to achieve HCV elimination. A priority is resourcing testing and treatment for Aboriginal and/or Torres Strait Islander people. Our findings support the need for novel and holistic healthcare strategies for PWID and the upscaling of Indigenous cultural approaches and interventions.

Acceptance and feasibility of a low-threshold and substitution services-based periodical monitoring system for blood-borne and sexually transmitted infections among people who inject drugs in Germany: a mixed-methods analysis

BACKGROUND

To reach the global elimination goals of viral hepatitis B and C (HBC, HCV), human immunodeficiency virus (HIV) and other sexually transmitted infections as a public health threat by 2030, monitoring is needed. Staff members of drug services and opioid substitution treatment (OST) practices in Berlin and Bavaria recruited clients for a pilot study addressing the respective infections among people who injected drugs (PWID) in Germany, 2021/2022. Participants filled a questionnaire and were tested for HBV, HCV, HIV and syphilis using dried blood spots (DBS). We evaluated the study design to implement a feasible and accepted nationwide periodical monitoring among PWID and serve as an example for the implementation of similar monitoring systems in other countries.

METHODS

A mixed-methods design was used, including focus group discussions with study participants and staff members and a semi-quantitative questionnaire filled by the latter. Aspects covered were the setting for recruitment, study preparation for staff members, willingness of clients to participate, the study questionnaire, blood collection and return of results.

RESULTS

The majority (96%) of 668 study participants were recruited in low-threshold services, drug consumption rooms and OST-practices. Flexibility of recruiting study participants during routine work or testing weeks/days was important to the facilities. Collaborations with local AIDS services helped cope with the work load of data collection. The need to train staff for DBS collection was highlighted. Study participants welcomed the testing opportunity in familiar places. Study participants frequently needed assistance to complete the study questionnaire. Return of results was considered as ethically mandatory by staff members but referral to treatment remained challenging.

CONCLUSIONS

For a successful monitoring time flexibility and adequate training are essential. Individual benefits for study participants by receiving their test results should be ensured and referral networks with infectiology practices may increase number of infected PWID receiving treatment. Overall, the evaluation confirmed that a monitoring through drug services and OST-practices is feasible and well accepted in Germany. Beyond that it shows important lessons learnt for the implementation in other countries.

Incidence of hepatitis C virus infection in the prison setting: The SToP-C study

People in prison are at high risk of HCV given high injecting drug use prevalence. This study evaluated HCV incidence and associated injecting drug use characteristics in prison. The SToP-C study enrolled people incarcerated in four Australian prisons. Participants were tested for HCV at enrolment and then every 3-6 months (October-2014 to November-2019). Participants eligible for this analysis included those at-risk of HCV primary infection (anti-HCV negative) or re-infection (anti-HCV positive, HCV RNA negative) with follow-up assessment. A total of 1643 eligible participants were included in analyses (82% male; median age 33 years; 30% injected drugs in prison; 1818 person-years of follow-up). Overall HCV incidence was 6.11/100 person-years (95%CI: 5.07-7.35), with higher rate of re-infection (9.34/100 person-years; 95%CI: 7.15-12.19) than primary infection (4.60/100 person-years; 95%CI: 3.56-5.96). In total population (n = 1643), HCV risk was significantly higher among participants injecting drugs in prison [vs. no injecting; adjusted hazard ratio (aHR): 10.55, 95%CI: 5.88-18.92), and those who were released and re-incarcerated during follow-up (vs. remained incarcerated; aHR: 1.60, 95%CI: 1.03-2.49). Among participants who injected recently (during past month, n = 321), HCV risk was reduced among those receiving high-dosage opioid agonist therapy (OAT), i.e. methadone ≥60 mg/day or buprenorphine ≥16 mg/day, (vs. no OAT, aHR: 0.11, 95%CI: 0.02-0.80) and increased among those sharing needles/syringes without consistent use of disinfectant to clean injecting equipment (vs. no sharing, HR: 4.60, 95%CI: 1.35-15.66). This study demonstrated high HCV transmission risk in prison, particularly among people injecting drugs. High-dosage OAT was protective, but improved OAT coverage and needle/syringe programmes to reduce sharing injecting equipment are required.