Injecting frequency trajectories and hepatitis C virus acquisition: Findings from a cohort of people who inject drugs in Montréal, Canada

Hyperfunctional T cell responses unchecked by regulatory T cells are unable to resolve hepaciviral infection without humoral contribution

BACKGROUND & AIMS

The most recent T cell-based vaccine against hepatitis C virus (HCV) in human subjects failed to swing the pendulum from chronicity to resolution despite eliciting cellular responses in the majority of individuals. These results naturally evoke the question of whether hyperactivated responses of a single adaptive immune arm are capable of inducing HCV clearance or if coordinated efforts between antibodies and T cells are indeed necessary. Here, we sought to address this point in determining whether the suppression of antiviral T cell and IgG responses by regulatory T cells (Tregs) is a critical prerequisite of delayed viral clearance or overt chronicity.

METHODS

Using a surrogate model of HCV infection, rodent hepacivirus (RHV) infection in mice, we utilized Foxp3-DTR mice to assess how Tregs modulate the generation of acute antiviral adaptive immune responses and indirectly dictate infection fate via intracellular flow cytometry staining, ELISA, RNA sequencing, and qPCR.

RESULTS

Transient depletion of Tregs prior to infection decreased viral-specific CD4+ T cell function, IgG production, and delayed viral clearance. In contrast, transient Treg depletion after infection increased both T cell functionality and IgG production, thereby facilitating accelerated viral clearance. Hyperactivated T cells, achieved via transient Treg depletion, were unable to clear the virus as an isolated effector arm without the help of viral-specific IgG production.

CONCLUSIONS

Tregs control the outcome of RHV infection via direct modulation of CD4+ T cells and IgG production. Hyperactivated T cell responses are incapable of compensating for experimentally induced lack of antibodies, further reinforcing the notion of cooperative interplay between adaptive immune arms in facilitating hepaciviral clearance.

IMPACT AND IMPLICATIONS

We demonstrate herein how timing of Treg depletion determines the fate of effector T cells, humoral responses, and the kinetics of viral clearance. Our observations provide direct evidence that functional T cell responses are incapable of compensating for suboptimal humoral responses in facilitating viral resolution. Our results imply that future HCV vaccine regimens should not solely rely on eliciting focused responses of a single effector arm, but rather incorporate immunogens capable of inducing durable features of both humoral and cellular memory.

Individual Heterogeneity and Trends in Hepatitis C Infection Risk Among People Who Inject Drugs: A Longitudinal Analysis

Hepatitis C virus (HCV) causes substantial morbidity and mortality, particularly among people who inject drugs (PWID). While elimination of HCV as a public health problem may be possible through treatment-as-prevention, reinfection can attenuate the impact of treatment scale-up. There is a need to better understand the distribution and temporal trends in HCV infection risk, including among HCV-seropositive individuals who will be eligible for treatment and at risk for subsequent reinfection. In this analysis of 840 seronegative and seropositive PWID in Baltimore, MD USA, we used random forest methods to develop a composite risk score of HCV infection from sociodemographic and behavioural risk factors. We characterised the individual heterogeneity and temporal trajectories in this composite risk score using latent class methods and compared that index with a simpler, conventional measure, injection drug use frequency. We found that 15% of the population remained at high risk of HCV infection and reinfection by the composite metric for at least 10 years from study enrolment, while others experienced transient periods of moderate and low risk. Membership in this high-risk group was strongly associated with higher rates of HCV seroconversion and post-treatment viraemia, as a proxy of reinfection risk. Injection frequency alone was a poor measure of risk, evidenced by the weak associations between injection frequency classes and HCV-associated outcomes. Together, our results indicate HCV infection risk is not equally distributed among PWID nor well captured by injection frequency alone. HCV elimination programmes should consider targeted, multifaceted interventions among high-risk individuals to reduce reinfection.

HIV and HCV seroincidence, associated factors and drug use in people who inject drugs, SurvUDI network, eastern central Canada, 1995-2020

BACKGROUND

The SurvUDI network is a biobehavioural survey among people who inject drugs (PWID) in Eastern Central Canada.

OBJECTIVES

The objectives were to describe HIV and HCV seroincidence trends, associated factors and changes in drug use behaviours.

METHODS

The network was initiated in 1995 and targets hard-to-reach, mostly out-of- treatment PWID. Participants were recruited mostly in harm reduction programs, completed an interviewer-administered questionnaire, provided a sample of gingival exudate for HIV and HCV antibody testing and were identified using an encrypted code allowing identification of multiple participations. Time trends were examined for HIV and HCV seroincidence, selected characteristics and behaviours. Cox proportional hazard regression was used to examine factors associated to HIV and HCV seroincidence.

RESULTS

Between January 1995 and March 2020, 15,907 individuals have completed 31,051 questionnaires. HIV seroincidence decreased significantly from 5.0 per 100 person-years (p-y) in 1995 to 0.4 per 100 p-y in 2018. HCV seroincidence also decreased significantly between 1998 and 2011. The use of syringes already used by someone else decreased significantly, from 43.4 % in 1995 to 12.4 % in 2019, as well as the use of equipment other than syringe already used by someone else. Cocaine/crack injection decreased significantly while "opioids other than heroin" injection increased, concomitant to daily injection. Injection with syringes already used by someone else and cocaine as the most often injected drug were significantly associated with HIV seroincidence (1995-2020). Injected opioid other than heroin, injected cocaine/crack, injected 100 or more times in the past month, injected for less than 3 years, injected with syringes or equipment already used by someone else, injected with someone else and reported client sex partners were significantly associated with HCV seroincidence (2004-2020).

CONCLUSION

HIV seroincidence and syringe/equipment sharing behaviour trends are encouraging, but HCV seroincidence remains high.

Real-world hepatitis C prevalence and treatment uptake at opioid agonist therapy clinics in Ontario, Canada

Widespread screening for hepatitis C virus (HCV) is necessary for Canada to meet its HCV elimination goals by 2030. People who currently or previously injected drugs are at high risk for HCV. Opioid agonist therapy (OAT, such as methadone and buprenorphine) has been shown to help stabilize the lives of people who are opioid-dependent. The distribution of OAT in North America typically requires daily, weekly, or monthly clinic visits and presents an opportunity for engagement, screening and treatment for those at high-risk of HCV. In this study, HCV screening was conducted by staff at OAT clinics in Ontario from 2016 to 2020 and those with chronic infections were treated on-site with direct-acting antivirals. Point-of-care or dried blood spot (DBS) testing was used for antibodies, DBS or serum for HCV RNA and serum for HCV RNA at SVR12 (sustained virological response). Clinics screened 1954 people (mean age 40 years ±12, 63% male). Forty-five percent were antibody positive, of whom 64% were HCV RNA+. Eighty percent of those RNA+ set an appointment in which 99% attended. Ninety-six percent started treatment with 87% completing treatment. Sixty-eight percent of people who completed treatment submitted a sample for SVR12 testing of which 97% achieved a virological cure. Results suggest that HCV screening and treatment at OAT clinics is feasible, effective and warrants expansion. Data suggest strong treatment adherence due to high rates of SVR12 comparable with other OAT-based HCV treatment programs. The lack of SVR12 sampling could be addressed by either on-site phlebotomy or incentivizing SVR12 sampling.

Legal Minors Who Inject: Differences in Socio-Demographics and Treatment Needs Compared to Adults in a Swedish National Sample of People with Injecting Drug Use

BACKGROUND

Injection drug use among legal minors is under-researched. Although the population may be small in absolute terms, treatment needs may be greater than for those who began injecting as adults. Such knowledge may help tailor services more effectively. Previous research tends to use selective samples or focuses solely on medical indicators. The present study uses a larger sample drawn from national register data in Sweden over a 9-year period (2013-2021) to analyze differences in medical and social treatment needs between people who began injecting as legal minors and their older counterparts.

METHOD

Data on first-time visitors to needle and syringe programmes (n = 8225, mean age 37.6, 26% women) were used. Historical socio-demographics and presenting treatment needs were compared between those with a debut injecting age under 18, and those who began injecting as adults.

RESULTS

The prevalence of injecting before 18 years was 29%. This group had more negative social circumstances, such as leaving school early, worse health, and greater service consumption, compared to those who began injecting as adults. In particular, they had been subjected to a greater level of control measures, such as arrest and compulsory care.

CONCLUSIONS

The present study shows that there are important health and social differences between those who inject prior to 18 and those who begin injecting as adults. This raises important questions for both child protection services and harm reduction approaches for legal minors who inject, who still qualify as 'children' in a legal and policy sense.

A cross-sectional study of hepatitis C prevalence and correlates among persons who inject drugs in rural and non-rural communities

Persons who inject drugs (PWID) have been experiencing a higher burden of new hepatitis C (HCV) due to the opioid epidemic. The greatest increases in injection have been in rural communities. However, less is known about the prevalence of HCV or its risk factors in rural compared to non-rural communities. This study compared HCV infection history, current infection, and associated behavioural and sociodemographic correlates among PWID recruited from rural and non-rural communities from Upstate New York (NY). This cross-sectional study recruited 309 PWID, using respondent-driven sampling. Blood samples were collected through finger stick for HCV antibody and RNA tests. A survey was also self-administered for HCV infection history, sociodemographics and behavioural correlates to compare by setting rurality. HCV seropositivity was significantly higher among PWID from rural than non-rural communities (71.0% vs. 46.8%), as was current infection (41.4% vs. 25.9%). High levels of past year syringe (44.4%) and equipment (62.2%) sharing were reported. Factors associated with infection history include syringe service program utilization, non-Hispanic white race, sharing needles and methamphetamine injection, which was higher in rural vs. non-rural communities (38.5% vs. 15.5%). HCV burden among PWID appears higher in rural than non-rural communities and may be increasing possibly due to greater levels of methamphetamine injection. On-going systematic surveillance of HCV prevalence and correlates is crucial to respond to the changing opioid epidemic landscape. Additionally, improving access to harm reduction services, especially with special focus on stimulants, may be important to reduce HCV prevalence among PWID in rural settings.

Association of co-occurring mental health problems with hepatitis C status among young people who inject drugs in rural New Mexico, 2016-2018

BACKGROUND

Injection drug use (IDU) remains the strongest risk factor for hepatitis C virus (HCV) in the United States. HCV rates are increasing in rural areas among young adult people who inject drugs (PWID). People with HCV and PWID have disproportionate rates of mental health problems; however, it is unclear whether risky injection behaviors mediate the association between mental health problems and HCV. We examined the association between mental health problems and HCV in a rural cohort of young adult PWID, with the goal of informing rural service delivery.

METHODS

We conducted a secondary analysis of cross-sectional data from a convenience sample of young adult PWID in 2 rural counties in New Mexico. Participants were recruited from 2 community venues between September 2016 and May 2018. Associations between mental health problems and HCV were examined using bivariate (Fisher's exact) and multivariable modified Poisson regression analyses (with robust standard errors). Using structural equation modeling (SEM), we assessed duration of IDU and receptive syringe sharing (RSS) as mediators of this relationship.

RESULTS

A total of 263 patients were enrolled, with a median age of 26.1 years. The majority were male (66.3%) and Hispanic/Latino (a) (87.6%). The median age first injected was 19 years, and over half reported having ever engaged in RSS (53.4%). At least one mental health problem was reported by 60.1% of participants, with post-traumatic stress disorder (PTSD) being the most prevalent condition (42.2%). A majority (60.9%) tested positive for HCV antibody, and just under half (45.7%) of all participants tested positive for HCV ribonucleic acid. In SEM, PTSD had a significant total effect on HCV (τ = 0.230, P = 0.05), and this relationship was partially mediated by duration of IDU (αβ = 0.077, P = 0.03). The association between mental health problems and HCV was partially mediated by duration of IDU and the sequential mediation of duration of IDU and RSS (αβ + αββ = 0.091, P = 0.05).

CONCLUSIONS

High HCV rates among young adult PWID in rural New Mexico may be partly explained by mental health problems, duration of IDU and RSS. Mental health services for young adult PWID in rural areas may help decrease HCV transmission in rural areas. Trial Registration N/A.