Treatment as prevention and cure towards global eradication of hepatitis C virus

Contemporary Insights into Hepatitis C Virus: A Comprehensive Review

Hepatitis C virus (HCV) remains a significant global health challenge. Approximately 50 million people were living with chronic hepatitis C based on the World Health Organization as of 2024, contributing extensively to global morbidity and mortality. The advent and approval of several direct-acting antiviral (DAA) regimens significantly improved HCV treatment, offering potentially high rates of cure for chronic hepatitis C. However, the promising aim of eventual HCV eradication remains challenging. Key challenges include the variability in DAA access across different regions, slightly variable response rates to DAAs across diverse patient populations and HCV genotypes/subtypes, and the emergence of resistance-associated substitutions (RASs), potentially conferring resistance to DAAs. Therefore, periodic reassessment of current HCV knowledge is needed. An up-to-date review on HCV is also necessitated based on the observed shifts in HCV epidemiological trends, continuous development and approval of therapeutic strategies, and changes in public health policies. Thus, the current comprehensive review aimed to integrate the latest knowledge on the epidemiology, pathophysiology, diagnostic approaches, treatment options and preventive strategies for HCV, with a particular focus on the current challenges associated with RASs and ongoing efforts in vaccine development. This review sought to provide healthcare professionals, researchers, and policymakers with the necessary insights to address the HCV burden more effectively. We aimed to highlight the progress made in managing and preventing HCV infection and to highlight the persistent barriers challenging the prevention of HCV infection. The overarching goal was to align with global health objectives towards reducing the burden of chronic hepatitis, aiming for its eventual elimination as a public health threat by 2030.

Exploring Knowledge and Awareness of HCV Infection and Screening Test: A Cross-Sectional Survey Among an Italian Sample

Addressing HCV represents a public health priority, especially in Italy, which has the highest HCV prevalence in Europe. This study primarily aimed to explore knowledge about the HCV infection and awareness of the existence of the HCV screening test in Italy, before the implementation of awareness campaigns in 2022. An online cross-sectional survey was conducted (December 2021-January 2022). The primary outcomes were: Disease Knowledge Score (DKS), Prevention and Transmission Knowledge Score (PTKS) (for both: scoring from 0 to 100%, higher scores corresponded to higher knowledge), and being unaware of the existence of the HCV screening. The final sample consisted of 813 participants. The median DKS was 75% (IQR = 66.7-83.3), the median PTKS was 46.2% (IQR = 38.5-53.8), and 23.2% of participants were unaware of HCV screening. Higher education, health-related study or profession, history of accidental injuries, being affected by HCV and having actively searched for information on HCV had positive associations with DKS. LGBT males showed significantly lower DKS. Considering PTKS, participants affected by HCV the disease had a negative association with this score. Having a postgraduate education reduced the likelihood of not knowing about the HCV screening test, while having at least one family member affected by hepatitis C increased this probability. This study highlighted a concerning lack of knowledge about prevention and transmission, indicating a need for targeted education campaigns. The findings emphasized the importance of information and motivation and identified male LGBT + individuals as a vulnerable group with limited disease knowledge. Future research should concern the effectiveness of awareness campaigns.

The best backbone for HIV prevention, treatment, and elimination: Emtricitabine+tenofovir

The advent of antiretroviral combination therapy has significantly impacted the HIV/AIDS epidemic. No longer a death sentence, HIV infection can be controlled and suppressed using cocktail therapies that contain two or more small molecule drugs. This review aims to highlight the discovery, development, and impact of one such molecule, namely, emtricitabine (FTC, emtriva), which is one of the most successful drugs in the fight against HIV/AIDS and has been taken by over 94% of individuals infected with HIV in the USA. We also pay tribute to Dr. John C. Martin, former CEO and Chairman of Gilead Sciences, who unexpectedly passed away in 2021. A true visionary, he was instrumental in delivering FTC, as part of combination therapy with TDF (tenofovir, viread) to the global stage. As the fight to eradicate HIV marches on, we honor Dr. Martin's legacy of collaboration, achievement, and hope.

Spatiotemporal Phylodynamics of Hepatitis C Among People Who Inject Drugs in India

BACKGROUND AND AIMS

Implementing effective interventions for HCV requires a detailed understanding of local transmission dynamics and geospatial spread. Little is known about HCV phylodynamics, particularly among high-burden populations, such as people who inject drugs (PWID).

APPROACH AND RESULTS

We used 483 HCV sequences and detailed individual-level data from PWID across four Indian cities. Bayesian phylogeographic analyses were used to evaluate transmission hotspots and geospatial diffusion of the virus. Phylogenetic cluster analysis was performed to infer epidemiologic links and factors associated with clustering. A total of 492 HIV sequences were used to draw comparisons within the same population and, in the case of coinfections, evaluate molecular evidence for shared transmission pathways. Overall, 139/483 (28.8%) of HCV sequences clustered with a median cluster size of 3 individuals. Genetically linked participants with HCV were significantly younger and more likely to be infected with HCV subtype 3b as well as to live and inject close to one another. Phylogenetic evidence suggests likely ongoing HCV infection/reinfection with limited support for shared HIV/HCV transmission pathways. Phylogeographic analyses trace historic HCV spread back to Northeastern India and show diffusion patterns consistent with drug trafficking routes.

CONCLUSIONS

This study characterizes HCV phylodynamics among PWID in a low and middle-income country setting. Heterogeneity and recent genetic linkage of HCV across geographically disparate Indian states suggest that targeted interventions could help prevent reimportation of virus through drug trafficking routes.

Excitable models: Projections, targets, and the making of futures without disease

In efforts to control disease, mathematical models and numerical targets play a key role. We take the elimination of a viral infection as a case for exploring mathematical models as 'evidence-making interventions'. Using interviews with mathematical modellers and implementation scientists, and focusing on the emergence of models of 'treatment-as-prevention' in hepatitis C control, we trace how projections detach from their calculative origins as social and policy practices. Drawing on the work of Michel Callon and others, we show that modelled projections of viral elimination circulate as 'qualculations', taking flight via their affects, including as anticipation. Modelled numerical targets do not need 'actual numbers' or precise measurements to perform their authority as evidence of viral elimination or as situated matters-of-concern. Modellers grapple with the ways that their models transform in policy and social practices, apparently beyond reasonable calculus. We highlight how practices of 'holding-on' to projections in relation to imaginaries of 'evidence-based' science entangle with the 'letting-go' of models beyond calculus. We conclude that the 'virtual precision' of models affords them fluid evidence-making potential. We imagine a different mode of modelling science in health, one more attuned to treating projections as qualculative, affective and relational, as excitable matter.

Early Treatment of COVID-19 Disease: A Missed Opportunity

Antivirals have demonstrated efficacy in treating other infectious diseases in early stages of disease, reducing morbidity, mortality, and the likelihood of onward transmission. At the time of writing, more than 1900 clinical trials are registered globally to assess the efficacy and safety of candidate therapeutics for COVID-19. The majority of these trials are designed to evaluate the comparative efficacy and safety of candidate therapeutics for the treatment of COVID-19 to prevent death among populations of hospitalized patients with advanced disease. Yet, emerging epidemiological evidence now indicates that the majority of those infected with the SARS-CoV-2, while still infectious, experience minimal or mild disease symptomology. Like HIV and hepatitis C that pioneered treatment as prevention, there is a missed opportunity for trials of early pharmaceutical intervention for COVID-19 disease evaluating not only reductions in morbidity and mortality but also transmissibility. We discuss this clinical research gap within an historical context of viral treatment as prevention for HIV and hepatitis C, and comment on the challenges and opportunities for clinical research of candidate therapeutics for early COVID-19 disease.

How to think with models and targets: Hepatitis C elimination as a numbering performance

The field of public health is replete with mathematical models and numerical targets. In the case of disease eliminations, modelled projections and targets play a key role in evidencing elimination futures and in shaping actions in relation to these. Drawing on ideas within science and technology studies, we take hepatitis C elimination as a case for reflecting on how to think with mathematical models and numerical targets as 'performative actors' in evidence-making. We focus specifically on the emergence of 'treatment-as-prevention' as a means to trace the social and material effects that models and targets make, including beyond science. We also focus on how enumerations are made locally in their methods and events of production. We trace the work that models and targets do in relation to three analytical themes: governing; affecting; and enacting. This allows us to situate models and targets as technologies of governance in the constitution of health, which affect and are affected by their material relations, including in relation to matters-of-concern which extend beyond calculus. By emphasising models and targets as enactments, we draw attention to how these devices give life to new enumerated entities, which detach from their calculative origins and take flight in new ways. We make this analysis for two reasons: first, as a call to bring the social and enumeration sciences closer together to speculate on how we might think with models and targets differently and more carefully; and second, to encourage an approach to science which treats evidencing-making interventions, such as models and targets, as performative and political.

Evaluating the population impact of hepatitis C direct acting antiviral treatment as prevention for people who inject drugs (EPIToPe) - a natural experiment (protocol)

INTRODUCTION

Hepatitis C virus (HCV) is the second largest contributor to liver disease in the UK, with injecting drug use as the main risk factor among the estimated 200 000 people currently infected. Despite effective prevention interventions, chronic HCV prevalence remains around 40% among people who inject drugs (PWID). New direct-acting antiviral (DAA) HCV therapies combine high cure rates (>90%) and short treatment duration (8 to 12 weeks). Theoretical mathematical modelling evidence suggests HCV treatment scale-up can prevent transmission and substantially reduce HCV prevalence/incidence among PWID. Our primary aim is to generate empirical evidence on the effectiveness of HCV 'Treatment as Prevention' (TasP) in PWID.

METHODS AND ANALYSIS

We plan to establish a natural experiment with Tayside, Scotland, as a single intervention site where HCV care pathways are being expanded (including specialist drug treatment clinics, needle and syringe programmes (NSPs), pharmacies and prison) and HCV treatment for PWID is being rapidly scaled-up. Other sites in Scotland and England will act as potential controls. Over 2 years from 2017/2018, at least 500 PWID will be treated in Tayside, which simulation studies project will reduce chronic HCV prevalence among PWID by 62% (from 26% to 10%) and HCV incidence will fall by approximately 2/3 (from 4.2 per 100 person-years (p100py) to 1.4 p100py). Treatment response and re-infection rates will be monitored. We will conduct focus groups and interviews with service providers and patients that accept and decline treatment to identify barriers and facilitators in implementing TasP. We will conduct longitudinal interviews with up to 40 PWID to assess whether successful HCV treatment alters their perspectives on and engagement with drug treatment and recovery. Trained peer researchers will be involved in data collection and dissemination. The primary outcome - chronic HCV prevalence in PWID - is measured using information from the Needle Exchange Surveillance Initiative survey in Scotland and the Unlinked Anonymous Monitoring Programme in England, conducted at least four times before and three times during and after the intervention. We will adapt Bayesian synthetic control methods (specifically the Causal Impact Method) to generate the cumulative impact of the intervention on chronic HCV prevalence and incidence. We will use a dynamic HCV transmission and economic model to evaluate the cost-effectiveness of the HCV TasP intervention, and to estimate the contribution of the scale-up in HCV treatment to observe changes in HCV prevalence. Through the qualitative data we will systematically explore key mechanisms of TasP real world implementation from provider and patient perspectives to develop a manual for scaling up HCV treatment in other settings. We will compare qualitative accounts of drug treatment and recovery with a 'virtual cohort' of PWID linking information on HCV treatment with Scottish Drug treatment databases to test whether DAA treatment improves drug treatment outcomes.

ETHICS AND DISSEMINATION

Extending HCV community care pathways is covered by ethics (ERADICATE C, ISRCTN27564683, Super DOT C Trial clinicaltrials.gov: NCT02706223). Ethical approval for extra data collection from patients including health utilities and qualitative interviews has been granted (REC ref: 18/ES/0128) and ISCRCTN registration has been completed (ISRCTN72038467). Our findings will have direct National Health Service and patient relevance; informing prioritisation given to early HCV treatment for PWID. We will present findings to practitioners and policymakers, and support design of an evaluation of HCV TasP in England.

Point-of-care Hepatitis C virus testing and linkage to treatment in an Australian inner-city emergency department

BACKGROUND

In Australia, Hepatitis C Virus (HCV) treatment is declining, despite broad access to direct-acting antiviral medication. People who inject drugs are proportionally over-represented in emergency department presentations. Emergency department assessment of people who have injected drugs for HCV presents an opportunity to engage this marginalised population with treatment. We describe the outcomes of risk-based screening and point-of-care anti-HCV testing for emergency department patients, and linkage to outpatient antiviral treatment.

METHODS

During the three-month study period, consecutive adult patients who presented to the emergency department during the study times were screened for risk factors and offered the OraQuick oral HCV antibody test. Those with reactive results were offered venepuncture in the emergency department for confirmatory testing and direct-acting antiviral treatment in clinic. The main outcome measures were the number and proportion of viremic participants that were linked to the hepatitis clinic, commenced treatment and achieved a sustained viral response. Secondary outcome measures were the proportion (%) of presentations screened that were oral antibody reactive, and the prevalence and type of HCV risk factors.

RESULTS

During the study period, 2408 of the 3931 (61%) presentations to the emergency department were eligible for screening. Of these 2408 patients, 1122 (47%) participated, 307 (13%) declined participation and 977 (41%) could not be approached during their time in the emergency department. Among the 1122 participants, 378 (34%) reported at least one risk factor. Subsequently, 368 (97%) of the 378 participants underwent OraQuick anti-HCV test, and 50 (14%) had a reactive result. A risk factor of ever having injected drugs was present in 44 (88%) of participants who were sero-positive. Of the 45 that had blood tested, 30 (67%) were HCV ribonucleic acid (RNA) positive. Three participants died. Of the 27 remaining participants, 10 (37%) commenced treatment and 7 of these 10 (70%) obtained a cure. There was a high rate of homelessness (24%) among anti-HCV positive participants.

CONCLUSION

Among emergency department participants with a risk factor for HCV, positive serology was common using a rapid point-of-care test. A history of injecting drug use was identified as the risk factor with highest yield for positive HCV serology, and is suitable as a single screening question. However, linkage to care post ED presentation was low in this marginalised population. There is a need for new pathways to improve the care cascade for marginalised individuals living with HCV infection.

Achievement of hepatitis C cascade of care milestones: a population-level analysis in Alberta, Canada

OBJECTIVES

Despite highly effective directly acting antiviral (DAA) therapy for hepatitis C virus (HCV), many patients do not receive treatment. We characterized the achievement of cascade of care milestones within 2 years of diagnosis among the Alberta population and evaluated variables associated with engagement at each stage.

METHODS

All Albertans with a first-time positive HCV antibody between 2009 and 2014 were included in this retrospective study. We determined which patients received follow-up testing (HCV RNA and HCV genotype), referral to hepatitis specialty care, and antiviral prescription, and achieved SVR within 2 years of diagnosis. Factors associated with achieving cascade milestones were identified by multivariable logistic regression analysis.

RESULTS

Of 6154 patients with HCV antibody and complete follow-up, 4238 (68.9%) had HCV RNA testing, 2360 (38.3%) had HCV genotyping, 2096 (34.1%) were assessed by a specialist, 711 (11.6%) were prescribed treatment and 207 (3.4%) achieved SVR within 2 years of diagnosis. Independent variables associated with reduced likelihood of achieving cascade milestones were Indigenous heritage (adjusted odds ratio (AOR) 0.53 (0.41-0.68) for HCV RNA testing), unstable housing (AOR 0.50 (0.32-0.79) for specialist assessment) and alcohol misuse (AOR 0.61 (0.38-0.99) for antiviral prescription). Men, older patients, patients with a higher income and patients with more advanced liver disease were more likely to achieve cascade of care milestones.

CONCLUSION

At each stage of patient engagement, opportunities for improvement were identified. Understanding the local cascade of care and factors associated with achieving cascade milestones will help prioritize initiatives to facilitate access to DAA therapy in Alberta.

System dynamics modeling of public health services provided by China CDC to control infectious and endemic diseases in China

BACKGROUND

Infectious and endemic diseases are a serious public health concern worldwide, and their prevention and treatment are globally controversial. This study aimed to establish an system dynamics (SD) model to analyze the factors influencing public health services provided by the Chinese Centers for Disease Control and Prevention (China CDC) to implement infectious and endemic disease control in China, by establishing more effective interventions to provide public health services and thus achieving the goal of controlling infectious and endemic diseases.

MATERIALS AND METHODS

An SD model was constructed using the Vensim DSS program. Intervention experiments were performed using the SD model, which reflected the influences on disease control by adjusting the governmental investment and compensation level for public health products.

RESULTS

The experimental results showed that increasing the governmental investment in China CDC and compensation level for public health products will significantly increase the public health product rate provided by China CDC.

DISCUSSION

Problems with infectious and endemic disease prevention and treatment are the result of the system's incomplete functioning and limited health resources. To address the current problems and improve the system, the government should increase its investment in the public health service system and improve the compensation system to ensure smooth implementation of infectious and endemic disease prevention and treatment and, ultimately, improve public health in China.

Understanding how, why, for whom, and under what circumstances opt-out blood-borne virus testing programmes work to increase test engagement and uptake within prison: a rapid-realist review

BACKGROUND

Prisons represent a unique opportunity to diagnose blood-borne viruses. Opt-out testing is receiving increasing interest, as a result of mounting evidence to suggest that the manner in which a test offer is delivered, affects test uptake. Although the effectiveness of opt-out testing within the prison setting has been established, robust explanations are required for the variation in outcomes reported.

METHODS

Rapid-realist review methodology was used to synthesise the literature on prison-based opt-out testing. The review was carried out in three phases. Phase one: An expert panel provided literature relevant to the implementation of opt-out testing within the English prison estate. Unstructured searches were also conducted to identify other social programmes where "opt-out" had been used to increase uptake. Phase two: a systematic search of six peer-review and five grey literature databases was carried out to identify empirical data on opt-out testing within the prison setting. Phase three: Additional non-exhaustive searches were carried out to identify literature that reinforced emergent concepts. The development of programme theory took place with each iteration and was validated in consultation with stakeholders.

RESULTS

Programme theory was constructed for two outcomes: the proportion of intake offered a test and the proportion offered that accepted testing. The proportion of intake offered testing was influenced by the timing of the test offer, which was often delayed due to barriers to prisoner access. The decision to accept testing was influenced by concerns about confidentiality, fear of a positive diagnosis, a prisoner's personal interpretation of risk, discomfort with invasive procedures, trust in healthcare, and the fidelity of the opt-out offer.

CONCLUSIONS

This review identified important implementation considerations that moderate the effectiveness of opt-out testing programmes. It also highlighted a lack of appreciation for the theoretical underpinnings of opt-out programmes and tension around how to implement testing in a manner that adheres to both default theory and informed consent. It is anticipated that results will be used to inform the design and implementation of subsequent versions of these programmes, as well as catalyse further in-depth analysis into their operation within the unique context of prison.

REVIEW REGISTRATION

CRD42017068342 .

Prevalence and mapping of hepatitis C infections among men who have sex with men in New York City

Emerging sexually transmitted hepatitis C virus (HCV) epidemics among men who have sex with men (MSM) have been reported worldwide, with higher HCV infection rates among those who are HIV-infected. This study aims to determine prevalence of recent and chronic HCV infections among community-recruited MSM in New York City (NYC), map HCV infections by home, social, and sexual neighborhoods, and identify clusters of genetically linked HCV variants using phylogenetic analysis. The NYC M2M study recruited MSM via modified time-space, venue-based sampling and internet/mobile app-based recruitment during 2010–13. Participants completed a Google Earth map on neighborhoods of where they lived, socialized, and had sex in the last 3 months, an ACASI questionnaire, and a sexual network inventory about their sex partners. The men received HIV testing and provided serum samples. Testing on stored serum samples included HCV antibody and RNA viral load, HCV antibody avidity assay (avidity index <30% with positive viral load is considered recently infected), and HCV RNA extraction and amplification to generate a 432 base-pair region of Core/E1 for sequencing and phylogenetic analysis. Historic local controls were included in the phylogenetic analysis. Of 1,028 MSM, 79.7% were HIV-negative and 20.3% HIV-positive. Twenty nine MSM (2.8%) were HCV antibody-positive. MSM who were HCV antibody-positive reported a median of 2 male sex partners in last 3 months, with 6.9% aged 18–24, 17.2% 25–29, 13.8% 30–39, and 62.1% 40 and over. 8.1% of HIV-positive MSM were HCV antibody-positive vs. 1.5% of HIV-negative men (p<0.0001). Of 29 HCV-antibody positive MSM, 12 (41%) were HCV RNA-positive (11 subtype 1a and 1 subtype 1b). Two of 12 HCV RNA-positive participants had low antibody avidity values, suggesting recent HCV infection. HCV antibody seropositivity was significantly associated with older age >40 years, adjusted odds ratio (aOR) 3.56 (95% CI 1.57, 8.08), HIV-positive serostatus, aOR 3.18 (95% CI 1.40, 7.22), any sexually transmitted infection (STI) in the last 3 months, aOR 2.81 (95% CI 1.11, 7.13), and injection drug use (IDU) ever, aOR 4.34 (95% CI 1.69, 11.17). Mapping of HCV infections differed slightly by home, social, and sexual neighborhoods. Based on phylogenetic analysis from 12 HCV RNA-positive samples, no evidence of a clustered HCV epidemic was found. Overall HCV seroprevalence was 2.8% among community-recruited MSM in NYC, with higher prevalence among HIV-positive MSM compared to HIV-negative MSM. Only two participants were found to have recent HCV infection, with no evidence of a clustered HCV epidemic based on phylogenetic analysis. Our results support testing of HCV infection among HIV-negative MSM if they report having a recent STI and IDU in the past rather than universal HCV testing in all HIV-negative MSM.

Estimated hepatitis C prevalence and key population sizes in San Francisco: A foundation for elimination

BACKGROUND

Initiated in 2016, End Hep C SF is a comprehensive initiative to eliminate hepatitis C (HCV) infection in San Francisco. The introduction of direct-acting antivirals to treat and cure HCV provides an opportunity for elimination. To properly measure progress, an estimate of baseline HCV prevalence, and of the number of people in various subpopulations with active HCV infection, is required to target and measure the impact of interventions. Our analysis was designed to incorporate multiple relevant data sources and estimate HCV burden for the San Francisco population as a whole, including specific key populations at higher risk of infection.

METHODS

Our estimates are based on triangulation of data found in case registries, medical records, observational studies, and published literature from 2010 through 2017. We examined subpopulations based on sex, age and/or HCV risk group. When multiple sources of data were available for subpopulation estimates, we calculated a weighted average using inverse variance weighting. Credible ranges (CRs) were derived from 95% confidence intervals of population size and prevalence estimates.

RESULTS

We estimate that 21,758 residents of San Francisco are HCV seropositive (CR: 10,274-42,067), representing an overall seroprevalence of 2.5% (CR: 1.2%- 4.9%). Of these, 16,408 are estimated to be viremic (CR: 6,505-37,407), though this estimate includes treated cases; up to 12,257 of these (CR: 2,354-33,256) are people who are untreated and infectious. People who injected drugs in the last year represent 67.9% of viremic HCV infections.

CONCLUSIONS

We estimated approximately 7,400 (51%) more HCV seropositive cases than are included in San Francisco's HCV surveillance case registry. Our estimate provides a useful baseline against which the impact of End Hep C SF can be measured.

The Strange, Expanding World of Animal Hepaciviruses

Hepaciviruses and pegiviruses constitute two closely related sister genera of the family Flaviviridae. In the past five years, the known phylogenetic diversity of the hepacivirus genera has absolutely exploded. What was once an isolated infection in humans (and possibly other primates) has now expanded to include horses, rodents, bats, colobus monkeys, cows, and, most recently, catsharks, shedding new light on the genetic diversity and host range of hepaciviruses. Interestingly, despite the identification of these many animal and primate hepaciviruses, the equine hepaciviruses remain the closest genetic relatives of the human hepaciviruses, providing an intriguing clue to the zoonotic source of hepatitis C virus. This review summarizes the significance of these studies and discusses current thinking about the origin and evolution of the animal hepaciviruses as well as their potential usage as surrogate models for the study of hepatitis C virus.

Respondent-driven sampling for identification of HIV- and HCV-infected people who inject drugs and men who have sex with men in India: A cross-sectional, community-based analysis

BACKGROUND

A major barrier to achieving ambitious targets for global control of HIV and hepatitis C virus (HCV) is low levels of awareness of infection among key populations such as men who have sex with men (MSM) and people who inject drugs (PWID). We explored the potential of a strategy routinely used for surveillance in these groups, respondent-driven sampling (RDS), to be used as an intervention to identify HIV- and HCV-infected PWID and MSM who are unaware of their status and those who are viremic across 26 Indian cities at various epidemic stages.

METHODS AND FINDINGS

Data were collected as part of the baseline assessment of an ongoing cluster-randomized trial. RDS was used to accrue participants at 27 sites (15 PWID sites and 12 MSM sites) selected to reflect varying stages of the HIV epidemic among MSM and PWID in India. A total of 56 seeds recruited a sample of 26,447 persons (approximately 1,000 participants per site) between October 1, 2012, and December 19, 2013. Across MSM sites (n = 11,997), the median age was 25 years and the median number of lifetime male partners was 8. Across PWID sites (n = 14,450), 92.4% were male, the median age was 30 years, and 87.5% reported injection in the prior 6 months. RDS identified 4,051 HIV-infected persons, of whom 2,325 (57.4%) were unaware of their HIV infection and 2,816 (69.5%) were HIV viremic. It also identified 5,777 HCV-infected persons, of whom 5,337 (92.4%) were unaware that they were infected with HCV and 4,728 (81.8%) were viremic. In the overall sample (both MSM and PWID), the prevalence of HIV-infected persons who were unaware of their status increased with sampling depth, from 7.9% in participants recruited in waves 1 through 5 to 12.8% among those recruited in waves 26 and above (p-value for trend < 0.001). The overall detection rate of people unaware of their HIV infection was 0.5 persons per day, and the detection rate of HIV-infected persons with viremia (regardless of their awareness status) was 0.7 per day. The detection rate of HIV viremic individuals was positively associated with underlying HIV prevalence and the prevalence of HIV viremia (linear regression coefficient per 1-percentage-point increase in prevalence: 0.05 and 0.07, respectively). The median detection rate of PWID who were unaware of their HCV infection was 2.5 per day. The cost of identifying 1 unaware HIV-infected individual ranged from US$51 to US$2,072 across PWID sites and from US$189 to US$5,367 across MSM sites. The mean additional cost of identifying 1 unaware HCV-infected PWID was US$13 (site range: US$7-US$140). Limitations of the study include the exclusivity of study sites to India, lack of prior HIV/HCV diagnosis confirmation with clinic records, and lack of cost data from other case-finding approaches commonly used in India.

CONCLUSIONS

In this study, RDS was able to rapidly identify at nominal cost a substantial number of unaware and viremic HIV-infected and HCV-infected individuals who were currently not being reached by existing programs and who were at high risk for transmission. Combining RDS (or other network-driven recruitment approaches) with strategies focused on linkage to care, particularly in high-burden settings, may be a viable option for achieving the 90-90-90 targets in key populations in resource-limited settings.

Value of Comprehensive HCV Treatment among Vulnerable, High-Risk Populations

OBJECTIVES

The objective of this study was to explore the trade-offs society and payers make when expanding treatment access to patients with chronic hepatitis C virus (HCV) infection in early stages of disease as well as to vulnerable, high-risk populations, such as people who inject drugs (PWID) and HIV-infected men who have sex with men (MSM-HIV).

METHODS

A discrete time Markov model simulated HCV progression and treatment over 20 years. Population cohorts were defined by behaviors that influence the risk of HCV exposure: PWID, MSM-HIV, an overlap cohort of individuals who are both PWID and MSM-HIV, and all other adults. Six different treatment scenarios were modeled, with varying degrees of access to treatment at different fibrosis stages and to different risk cohorts. Benefits were measured as quality-adjusted life-years and a $150,000/quality-adjusted life-year valuation was used to assess social benefits.

RESULTS

Compared with limiting treatment to METAVIR fibrosis stages F3 or F4 and excluding PWID, expanding treatment to patients in all fibrosis stages and including PWID reduces cumulative new infections by 55% over a 20-year horizon and reduces the prevalence of HCV by 93%. We find that treating all HCV-infected individuals is cost saving and net social benefits are over $500 billion greater compared with limiting treatment. Including PWID in treatment access saves 12,900 to 41,200 lives.

CONCLUSIONS

Increased access to treatment brings substantial value to society and over the long-term reduces costs for payers, as the benefits accrued from long-term reduction in prevalent and incident cases, mortality, and medical costs outweigh the cost of treatment.

Incidence of hepatitis C in HIV positive and negative men who have sex with men 2000-2016: a systematic review and meta-analysis

BACKGROUND

There is a need for systematic reviews and meta-analyses to synthesize the epidemiology, and the riskfactors for hepatitis C virus (HCV) among HIV-coinfected and HIV negative men who have sex with men (MSM).

METHODS

A meta-analysis of 28 studies was carried out by pooling HCV incidence data of HIV-coinfected and HIV negative MSM. Differences in incidence outcome depending on the prospective or retrospective nature of the individual studies were investigated.

RESULTS

The pooled incidence of HCV in MSM was 6.3 per 1000 person-years (95% CI 5.0-7.5). The overall estimated incidence was 19-fold higher in HIV positive compared to HIV negative MSM living in resource-rich countries. This result was confirmed when the analysis was restricted to high-quality studies. Factors associated with an increased risk for incident HCV included behavioural factors (sexual risk behaviour and recreational drug use) as well as biological characteristics (HIV coinfection and a recent history of syphilis).

CONCLUSION

In conclusion, incident HCV predominantly affects HIV positive MSM. The incidence rate varied largely between studies, factors such as study design might play an important role.

Global genotype distribution of hepatitis C viral infection among people who inject drugs

BACKGROUND & AIMS

Hepatitis C viral infection (HCV) after injection drug use is very prevalent. The kind of genotype determines the response to treatment. However, no systematic review update on the global genotype distribution of HCV in people who inject drugs (PWID) is currently available.

METHODS

A systematic review was performed by using the keywords: Genotype, Hepatitis C, Injection drug user/Intravenous drug user/Substance user/ PWID, Name of countries in Pubmed, Embase and PsycINFO. The results were compared with the review of Gower et al. in 2014, concerning the distribution of HCV genotypes in the general HCV population.

RESULTS

Using these keywords, 132 studies in 48 countries (from 1995 to 2015) were collected. After grading these results, the data of 48 studies were used to determine the distribution of genotypes in PWID. Genotype 1 is the most prevalent genotype all over the world in PWID. In Europe, genotypes 1, 3 and 4 are highly prevalent. In North and South America and in Australia genotype 1 and 3 are most prevalent. In Asia genotype 2 and 6, and Africa genotype 1a and 4 are mostly observed. Overall, the most important differences comparing with the general population are a lower prevalence of genotype 1b in the PWID population and higher prevalence of genotype 1a and 3.

CONCLUSIONS

There is a different prevalence of genotype distribution in PWID than in the general population. Genotype 3 is especially highly prevalent in the Western countries.

LAY SUMMARY

Hepatitis C viral infection after injection drug use is very prevalent. The most important genotype causing HCV infection in PWID globally is genotype 1, as is the case in the general population, but also genotype 3 is highly prevalent in PWID. Genotype 4 is most prevalent in Africa, spreading into Europe, whereas genotype 2 and 6 are more located in Asia. The most important difference comparing to the general population are generally lower prevalence of genotype 1b, and higher prevalence of genotype 1a and 3 in PWID. As the genotype nowadays still determines the treatment, and as there is a different genotype distribution than in the general population, it is important to identify the genotype also in PWID.

Future landscape of hepatitis C research - Basic, translational and clinical perspectives

With the latest all-oral interferon- and ribavirin-free regimens based on direct acting antivirals against the hepatitis C virus (HCV), sustained virological response rates of >90% are achieved, which is equivalent to cure. This has become possible for all genotypes and all subgroups of patients, including many of the most difficult-to-treat populations so far. Since a prophylactic HCV vaccine is not yet available, control of HCV infection will for the time being have to rely on the use of effective and safe antiviral treatments as well as their accessibility and affordability. Different approaches may apply to different parts of the world, eradication of HCV representing a major long-term goal. Whether hepatitis C becomes the first chronic viral infection to be eradicated without a prophylactic vaccine remains to be shown. Here, we briefly summarize advances in the molecular virology of hepatitis C, highlight lessons of biological relevance that were learned through the study of HCV, and its translational and clinical implications. We have also listed selected unsolved challenges, emphasizing that HCV is a unique model and that advances in this direction may yield knowledge of broad biological significance, novel technologies and insights into related important human pathogens.

Polyanionic carbosilane dendrimers prevent hepatitis C virus infection in cell culture

Hepatitis C virus (HCV) infection is a major biomedical problem worldwide. Although new direct antiviral agents (DAAs) have been developed for the treatment of chronic HCV infection, the potential emergence of resistant virus variants and the difficulties to implement their administration worldwide make the development of novel antiviral agents an urgent need. Moreover, no effective vaccine is available against HCV and transmission of the virus still occurs particularly when prophylactic measures are not taken. We used a cell-based system to screen a battery of polyanionic carbosilane dendrimers (PCDs) to identify compounds with antiviral activity against HCV and show that they inhibit effective virus adsorption of major HCV genotypes. Interestingly, one of the PCDs irreversibly destabilized infectious virions. This compound displays additive effect in combination with a clinically relevant DAA, sofosbuvir. Our results support further characterization of these molecules as nanotools for the control of hepatitis C virus spread.

Health Disparities in Hepatitis C Screening and Linkage to Care at an Integrated Health System in Southeast Michigan

With recommended screening for hepatitis C among the 1945–1965 birth cohort and advent of novel highly effective therapies, little is known about health disparities in the Hepatitis C care cascade. Our objective was to evaluate hepatitis C screening rates and linkage to care, among patients who test positive, at our large integrated health system. We used electronic medical records to retrospectively identify patients, in the birth cohort, who were seen in 21 Internal Medicine clinics from July 2014 to June 2015. Patients previously screened for hepatitis C and those with established disease were excluded. We studied patients’ sociodemographic and medical conditions along with provider-specific factors associated with likelihood of screening. Patients who tested positive for HCV antibody were reviewed to assess appropriate linkage to care and treatment. Of 40,561 patients who met inclusion criteria, 21.3% (8657) were screened, 1.3% (109) tested positive, and 30% (30/100) completed treatment. Multivariate logistic regression showed that African American race, male gender, electronic health engagement, residency teaching clinic visit, and having more than one clinic visit were associated with higher odds of screening. Patients had a significant decrease in the likelihood of screening with sequential interval increase in their Charlson comorbidity index. When evaluating hepatitis C treatment in patients who screened positive, electronic health engagement was associated with higher odds of treatment whereas Medicaid insurance was associated with significantly lower odds. This study shows that hepatitis C screening rates and linkage to care continue to be suboptimal with a significant impact of multiple sociodemographic and insurance factors. Electronic health engagement emerges as a tool in linking patients to the hepatitis C care cascade.

Clinicians' Views of Hepatitis C Virus Treatment Candidacy With Direct-Acting Antiviral Regimens for People Who Inject Drugs

BACKGROUND

Direct-acting antivirals (DAAs) are curative in most persons with chronic hepatitis C virus (HCV) infection. However, high cost and concerns about adherence and reinfection may present continued barriers to treatment, particularly for people who inject drugs (PWID).

OBJECTIVE

To understand changes in assessments of treatment candidacy, given advances in treatment.

METHODS

Clinicians attending the Liver Meeting® in 2014 who reported prescribing HCV treatment in the past three years were invited to complete a survey regarding HCV treatment decisions. Participants assessed their likelihood to treat HCV in PWID in association with time of abstinence from injection drug use and what impacts their decision to provide treatment using interferon and DAAs.

RESULTS

108 clinicians completed the survey; 10% were willing to treat an active PWID (last injection within 30 days) using interferon-containing regimens, and 15% with all-oral regimens. For each increasing time interval of injection abstinence, there was an increase in the odds of a clinician reporting willingness to treat with DAAs (Odds Ratio (OR) 2.57, 95% CI 2.18, 3.03) and with interferon-based treatment (OR 2.22 (95% CI 1.90, 2.61), Reinfection and medication cost were cited as most important concerns when determining candidacy.

CONCLUSIONS

A cure is now the norm in HCV treatment, and there is an increasing need to address the barriers to treating PWID, the population with the highest burden of infection. Understanding treatment candidacy assessments is essential to improving uptake. This study provides insight into how clinicians view treatment candidacy in this era of DAAs and can help identify supportive treatment environments and concurrent programs.

Biochemical Characterization of the Active Anti-Hepatitis C Virus Metabolites of 2,6-Diaminopurine Ribonucleoside Prodrug Compared to Sofosbuvir and BMS-986094

Ribonucleoside analog inhibitors (rNAI) target the hepatitis C virus (HCV) RNA-dependent RNA polymerase nonstructural protein 5B (NS5B) and cause RNA chain termination. Here, we expand our studies on β-d-2'-C-methyl-2,6-diaminopurine-ribonucleotide (DAPN) phosphoramidate prodrug 1 (PD1) as a novel investigational inhibitor of HCV. DAPN-PD1 is metabolized intracellularly into two distinct bioactive nucleoside triphosphate (TP) analogs. The first metabolite, 2'-C-methyl-GTP, is a well-characterized inhibitor of NS5B polymerase, whereas the second metabolite, 2'-C-methyl-DAPN-TP, behaves as an adenosine base analog. In vitro assays suggest that both metabolites are inhibitors of NS5B-mediated RNA polymerization. Additional factors, such as rNAI-TP incorporation efficiencies, intracellular rNAI-TP levels, and competition with natural ribonucleotides, were examined in order to further characterize the potential role of each nucleotide metabolite in vivo Finally, we found that although both 2'-C-methyl-GTP and 2'-C-methyl-DAPN-TP were weak substrates for human mitochondrial RNA (mtRNA) polymerase (POLRMT) in vitro, DAPN-PD1 did not cause off-target inhibition of mtRNA transcription in Huh-7 cells. In contrast, administration of BMS-986094, which also generates 2'-C-methyl-GTP and previously has been associated with toxicity in humans, caused detectable inhibition of mtRNA transcription. Metabolism of BMS-986094 in Huh-7 cells leads to 87-fold higher levels of intracellular 2'-C-methyl-GTP than DAPN-PD1. Collectively, our data characterize DAPN-PD1 as a novel and potent antiviral agent that combines the delivery of two active metabolites.

Review article: treatment as prevention - targeting people who inject drugs as a pathway towards hepatitis C eradication

BACKGROUND

Hepatitis C virus (HCV) is a leading cause of chronic liver disease worldwide. HCV predominates in people who inject drugs; a group in whom anti-viral therapy has previously been withheld on the basis of chaotic lifestyles and associated risks of reinfection. New research has emerged which suggests that by specifically targeting HCV-infected people who inject drugs for treatment, the pool of HCV would deplete, thus reducing overall transmission and eventually leading to HCV eradication.

AIM

To outline the requirements for HCV eradication and review the evidence that this is achievable.

METHODS

Expert review of the literature.

RESULTS

The achievement of HCV eradication using 'treatment as prevention' is supported by numerous epidemiological modelling studies employing a variety of models in several contexts including people who inject drugs, men who have sex with men and prisoners. More recent studies also incorporate the newer, more efficacious direct-acting anti-viral drugs. These drugs have been shown to be safe and effective in people who inject drugs in clinical trials. There is no empirical evidence of the impact of treatment as prevention strategies on population prevalence.

CONCLUSIONS

This review highlights the efforts to control HCV and evaluates the possibilities of achieving eradication of HCV. Currently, the technologies required to achieve HCV eradication exist, but the infrastructure to deliver them is not generally available or of insufficient scale outside of specific areas. Such areas are yet to demonstrate that elimination is possible, but results of studies in these areas are awaited. Such a demonstration would be proof of principle for eradication. Although we are aspiring towards HCV eradication, elimination is the more realistic prospect.

Hepatitis C Virus E1 and E2 Proteins Used as Separate Immunogens Induce Neutralizing Antibodies with Additive Properties

Various strategies involving the use of hepatitis C virus (HCV) E1 and E2 envelope glycoproteins as immunogens have been developed for prophylactic vaccination against HCV. However, the ideal mode of processing and presenting these immunogens for effective vaccination has yet to be determined. We used our recently described vaccine candidate based on full-length HCV E1 or E2 glycoproteins fused to the heterologous hepatitis B virus S envelope protein to compare the use of the E1 and E2 proteins as separate immunogens with their use as the E1E2 heterodimer, in terms of immunogenetic potential and the capacity to induce neutralizing antibodies. The specific anti-E1 and anti-E2 antibody responses induced in animals immunized with vaccine particles harboring the heterodimer were profoundly impaired with respect to those in animals immunized with particles harboring E1 and E2 separately. Moreover, the anti-E1 and anti-E2 antibodies had additive neutralizing properties that increase the cross-neutralization of heterologous strains of various HCV genotypes, highlighting the importance of including both E1 and E2 in the vaccine for an effective vaccination strategy. Our study has important implications for the optimization of HCV vaccination strategies based on HCV envelope proteins, regardless of the platform used to present these proteins to the immune system.

MEAN inhibits hepatitis C virus replication by interfering with a polypyrimidine tract-binding protein

MEAN (6‐methoxyethylamino‐numonafide) is a small molecule compound, and here, we report that it effectively inhibits hepatitis C virus (HCV) infection in an HCV cell culture system using a JC1‐Luc chimeric virus, with a 50% effective concentration (EC50) of 2.36 ± 0.29 μM. Drug combination usage analyses demonstrated that MEAN was synergistic with interferon α, ITX5061 and ribavirin. In addition, MEAN effectively inhibits N415D mutant virus and G451R mutant viral infections. Mechanistic studies show that the treatment of HCV‐infected hepatocytes with MEAN inhibits HCV replication but not translation. Furthermore, treatment with MEAN significantly reduces polypyrimidine tract‐binding protein (PTB) levels and blocks the cytoplasmic redistribution of PTB upon infection. In the host cytoplasm, PTB is directly associated with HCV replication, and the inhibition of HCV replication by MEAN can result in the sequestration of PTB in treated nuclei. Taken together, these results indicate that MEAN is a potential therapeutic candidate for HCV infection, and the targeting of the nucleo‐cytoplasmic translocation of the host PTB protein could be a novel strategy to interrupt HCV replication.

Hepatitis C virus treatment as prevention in people who inject drugs: testing the evidence

PURPOSE OF REVIEW

The majority of hepatitis C virus (HCV) infections in the United Kingdom and many developing countries were acquired through injecting. New clinical guidance suggests that HCV treatment should be offered to people with a transmission risk - such as people who inject drugs (PWID) - irrespective of severity of liver disease. We consider the strength of the evidence base and potential problems in evaluating HCV treatment as prevention among PWID.

RECENT FINDINGS

There is good theoretical evidence from dynamic models that HCV treatment for PWID could reduce HCV chronic prevalence and incidence among PWID. Economic evaluations from high-income settings have suggested HCV treatment for PWID is cost-effective, and that in many settings HCV treatment of PWID could be more cost-effective than treating those at an equivalent stage with no ongoing transmission risk. Epidemiological studies of older interferon treatments have suggested that PWID can achieve similar treatment outcomes to other patient groups treated for chronic HCV. Impact and cost-effectiveness of HCV treatment is driven by the potential 'prevention benefit' of treating PWID. Model projections suggest that more future infections, end stage liver disease, and HCV-related deaths will be averted than lost through reinfection of PWID treated successfully for HCV. However, there is to date no empirical evidence from trials or observational studies that test the model projections and 'prevention benefit' hypothesis. In part this is because of uncertainty in the evidence base but also there is unlikely to have been a change in HCV prevalence due to HCV treatment because PWID HCV treatment rates historically in most sites have been low, and any scale-up and switch to the new direct acting antiviral has not yet occurred. There are a number of key uncertainties in the data available on PWID that need to be improved and addressed to evaluate treatment as prevention. These include estimates of the prevalence of PWID, measurements of HCV chronic prevalence and incidence among PWID, and how to interpret reinfection rates as potential outcome measures.

SUMMARY

Eliminating HCV through scaling up treatment is a theoretical possibility. But empirical data are required to demonstrate that HCV treatment can reduce HCV transmission, which will require an improved evidence base and analytic framework for measuring PWID and HCV prevalence.

The hepatitis C virus epidemics in key populations (including people who inject drugs, prisoners and MSM): the use of direct-acting antivirals as treatment for prevention

PURPOSE OF REVIEW

The burden of hepatitis C virus (HCV) is high among people who inject drugs (PWID) and prisoners, and increasing among HIV-infected MSM, who are key populations for HCV transmission in high-income countries and may also play a role in many in low- and middle-income countries. There is an increasing interest in the use of HCV antiviral treatment for prevention in these populations.

RECENT FINDINGS

Numerous theoretical modelling studies have explored the potential impact of HCV treatment for prevention among PWID in a range of global settings, generally finding that modest and achievable levels of HCV treatment, especially with interferon-free direct-acting antiviral therapy (IFN-free DAAs), could substantially reduce HCV chronic prevalence among PWID within the next 10-20 years. In addition, modelling studies have shown HCV testing and treatment in prison (including prevention benefits) could be cost-effective if continuity of care is ensured, or HCV treatments are shortened with DAAs. Modelling work among HIV-infected MSM has shown that further HCV treatment scale-up is likely required despite high treatment rates in this population. However, no empirical studies have explored whether HCV treatment can reduce HCV prevalence and prevent onwards transmission among those at risk of transmission.

SUMMARY

HCV treatment for key populations such as PWID, prisoners and MSM could become an important HCV prevention intervention, especially in the IFN-free DAA era. However, there is an urgent need to test these hypotheses through empirical studies.

The role of a hepatitis C virus vaccine: modelling the benefits alongside direct-acting antiviral treatments

BACKGROUND

Hepatitis C virus (HCV) elimination is being seriously considered globally. Current elimination models require a combination of highly effective HCV treatment and harm reduction, but high treatment costs make such strategies prohibitively expensive. Vaccines should play a key role in elimination but their best use alongside treatments is unclear. For three vaccines with different efficacies we used a mathematical model to estimate the additional reduction in HCV prevalence when vaccinating after treatment; and to identify in which settings vaccines could most effectively reduce the number of treatments required to achieve fixed reductions in HCV prevalence among people who inject drugs (PWID).

METHODS

A deterministic model of HCV transmission among PWID was calibrated for settings with 25, 50 and 75% chronic HCV prevalence among PWID, stratified by high-risk or low-risk PWID. For vaccines with 30, 60 or 90% efficacies, different rates of treatment and vaccination were introduced. We compared prevalence reductions achieved by vaccinating after treatment to prevent reinfection and vaccinating independently of treatment history in the community; and by allocating treatments and vaccinations to specific risk groups and proportionally across risk groups.

RESULTS

Vaccinating after treatment was minimally different to vaccinating independently of treatment history, and allocating treatments and vaccinations to specific risk groups was minimally different to allocating them proportionally across risk groups. Vaccines with 30 or 60% efficacy provided greater additional prevalence reduction per vaccination in a setting with 75% chronic HCV prevalence among PWID than a 90% efficacious vaccine in settings with 25 or 50% chronic HCV prevalence among PWID.

CONCLUSIONS

Vaccinating after treatment is an effective and practical method of administration. In settings with high chronic HCV prevalence among PWID, even modest coverage with a low-efficacy vaccine could provide significant additional prevalence reduction beyond treatment alone, and would likely reduce the cost of achieving prevalence reduction targets.

Lack of health insurance limits the benefits of hepatitis C virus screening: insights from the National Health and Nutrition Examination Hepatitis C follow-up study

OBJECTIVES

Identifying barriers to access to hepatitis C virus (HCV) treatment among screen detected subjects is critical for any public health strategy aimed at controlling HCV infection in the general population.

METHODS

Data from the National Health and Nutrition Examination Survey HCV Follow-up study from 2001 to 2010 were used. Participants who tested positive for HCV were sent a letter informing them of their test results and advised to pursue further evaluation. Information on HCV transmission and its potential complications was also provided to all positive participants. These subjects were recontacted 6 months after notification to determine what action they had taken regarding the positive result.

RESULTS

Of 38,025 participants, 502 tested positive for HCV infection, giving a prevalence of 1.3% (95% confidence interval (CI) 0.8%, 1.8%). A total of 205 subjects participated in the 6-month follow-up interview. Those who could not be reached were more likely to be less educated, injecting drugs, and not to have health insurance. Half (50.2%) of the positive individuals were not aware of their status before notification. A total of 166 (81%) had pursued further evaluation. Only 18 (26.9%) received therapy. The main reason for not receiving treatment was high cost (19.4%). In adjusted analysis, the only barrier to pursuing downstream HCV care was the lack of health insurance (2.76, 95% CI 1.54, 7.69; P=0.007).

CONCLUSIONS

This study suggests that the lack of health insurance may attenuate the theoretical benefits of a screening program that identifies asymptomatic HCV-infected individuals who are less likely to pursue downstream care.

Hepatitis C virus: why do we need a vaccine to prevent a curable persistent infection?

Chronic hepatitis C virus infection is now curable by antiviral therapy but the global burden of liver disease is unlikely to diminish without a vaccine to prevent transmission. The objective of HCV vaccination is not to induce sterilizing immunity, but instead to prevent persistent infection. One vaccine that incorporates only non-structural HCV proteins is now in phase I/II efficacy trials to test the novel concept that T cell priming alone is sufficient for protection. Evidence also suggests that antibodies contribute to infection resolution. Vaccines comprised of recombinant envelope glycoproteins targeted by neutralizing antibodies have been assessed in humans for immunogenicity. Here, we discuss current concepts in protective immunity and divergent approaches to vaccination against a highly mutable RNA virus.

The promise of treatment as prevention for hepatitis C: Meeting the needs of people who inject drugs?

Treatment as prevention (TasP) is a concept common to the HIV sector. In this commentary we draw on the literature addressing HIV and HCV TasP, alongside qualitative HCV research, to critically appraise the promise of TasP for HCV and assess the needs of PWID in the future of HCV care. With the advent of highly effective direct-acting antiviral HCV treatments, TasP is now under consideration for HCV. A growing body of literature documents numerous social structural barriers to HCV treatment access and uptake for PWID, among whom HCV is highly prevalent. Yet these barriers - and suggestions for surmounting them - are rarely included in emergent literature on HCV TasP. Although HCV TasP has important advocacy potential for increasing treatment access among PWID, critical reflection on its implications are warranted. We outline potential limitations of TasP for HCV and the conditions under which it might be optimised. We argue that HCV treatment as a prevention strategy can only be realisable in a context of enhanced harm reduction access, meaningful community engagement, and enabling environment interventions informed by the needs and perspectives of PWID.

Hepatitis C virus treatment as prevention among injecting drug users: who should we cure first?

BACKGROUND AND AIMS

Treatment of injecting drug users (IDU) for hepatitis C virus (HCV) infection may prevent onward transmission. Treating individuals who often share injecting equipment is most likely to prevent new infections. However, these high-risk IDU are also more likely to become re-infected than low-risk IDU. We investigated to which group treatment is best targeted.

DESIGN

We modelled the expected benefits per treatment of one chronically HCV-infected IDU in a population of low- and high-risk IDU. The benefits of treating one low- or one high-risk IDU were compared.

MEASUREMENTS

Benefits included the probability for the treated IDU to become and remain uninfected, as well as the expected number of prevented infections to others (i.e. we quantified the total expected decrease in chronic infections).

FINDINGS

We found a threshold in HCV-RNA prevalence above which treating low-risk IDU, and below which treating high-risk IDU, resulted in the greatest benefits. This threshold was at 50% of exchanged syringes being HCV contaminated. When 42% of IDU engaged in high-risk behaviour (borrowing and lending out syringes 7.3 times more frequently than low-risk IDU), the corresponding threshold of HCV-RNA prevalence among IDU was at 32%. Larger-risk heterogeneity led to a lower corresponding threshold among IDU. A combination of HCV treatment and 50% risk reduction was best directed at high-risk IDU for prevalence among syringes up to 59%. The threshold was marginally sensitive to changes in disease and treatment variables.

CONCLUSIONS

When more than half of all exchanged syringes in a population of injecting drug users (IDU) are contaminated by hepatitis C virus, it is most efficient to treat low-risk IDU first. Below this threshold, it is most efficient to treat high-risk IDU first.

A public health approach to hepatitis C control in low- and middle-income countries

In light of new treatment regimens for hepatitis C, Amitabh Suthar and Anthony Harries outline a wider public health approach for tackling the disease.

Chimeric hepatitis B virus (HBV)/hepatitis C virus (HCV) subviral envelope particles induce efficient anti-HCV antibody production in animals pre-immunized with HBV vaccine

The development of an effective, affordable prophylactic vaccine against hepatitis C virus (HCV) remains a medical priority. The recently described chimeric HBV-HCV subviral envelope particles could potentially be used for this purpose, as they could be produced by industrial procedures adapted from those established for the hepatitis B virus (HBV) vaccine. We show here, in an animal model, that pre-existing immunity acquired through HBV vaccination does not influence the immunogenicity of the HCV E2 protein presented by these chimeric particles. Thus, these chimeric HBV-HCV subviral envelope particles could potentially be used as a booster in individuals previously vaccinated against HBV, to induce protective immunity to HCV.

Burden of hepatitis C virus disease and access to hepatitis C virus services in people who inject drugs in India: a cross-sectional study

BACKGROUND

90% of individuals infected with hepatitis C virus (HCV) worldwide reside in resource-limited settings. We aimed to characterise the prevalence of HCV, HIV/HCV co-infection, and the HCV care continuum in people who inject drugs in India.

METHODS

14 481 people (including 31 seeds--individuals selected as the starting point for sampling because they were well connected in the drug using community) who inject drugs were sampled from 15 cities throughout India using respondent-driven sampling from Jan 2, 2013 to Dec 19, 2013. Data from seeds were excluded from all analyses. HCV prevalence was estimated by the presence of anti-HCV antibodies incorporating respondent-driven sampling weights. HCV care continuum outcomes were self-reported except for viral clearance in treatment-experienced participants.

FINDINGS

The median age of participants was 30 years (IQR 24-36) and 13 608 (92·4%) of 14 449 were men (data were missing for some variables). Weighted HCV prevalence was 5777 (37·2%) of 14 447; HIV/HCV co-infection prevalence was 2085 (13·2%) of 14 435. Correlates of HCV infection included high lifetime injection frequency, HIV positivity, and a high prevalence of people with HIV RNA (more than 1000 copies per mL) in the community. Of the 5777 people who inject drugs that were HCV antibody positive, 440 (5·5%) were aware of their status, 225 (3·0%) had seen a doctor for their HCV, 79 (1·4%) had taken HCV treatment, and 18 (0·4%) had undetectable HCV RNA. Of 12 128 participants who had not previously been tested for HCV, 6138 (50·5%) did not get tested because they had not heard of HCV. In the 5777 people who were HCV antibody positive, 2086 (34·4%) reported harmful or hazardous alcohol use, of whom 1082 (50·4%) were dependent, and 3821 (65·3%) reported needle sharing. Awareness of HCV positive status was significantly associated with higher education, HIV testing history, awareness of HIV positive status, and higher community antiretroviral therapy coverage.

INTERPRETATION

The high burden of HCV and HIV/HCV co-infection coupled with low-access to HCV services emphasises an urgent need to include resource-limited settings in the global HCV agenda. Although new treatments will become available worldwide in the near future, programmes to improve awareness and reduce disease progression and transmission need to be scaled up without further delay. Failure to do so could result in patterns of rising mortality, undermining advances in survival attributed to widespread HIV treatment.

FUNDING

US National Institutes of Health.

Comparative molecular dynamics simulation of Hepatitis C Virus NS3/4A protease (Genotypes 1b, 3a and 4b) predicts conformational instability of the catalytic triad in drug resistant strains

The protease domain of the Hepatitis C Virus (HCV) nonstructural protein 3 (NS3) has been targeted for inhibition by several direct-acting antiviral drugs. This approach has had marked success to treat infections caused by HCV genotype 1 predominant in the USA, Europe, and Japan. However, genotypes 3 and 4, dominant in developing countries, are resistant to a number of these drugs and little progress has been made towards understanding the structural basis of their drug resistivity. We have previously developed a 4D computational methodology, based on 3D structure modeling and molecular dynamics simulation, to analyze the active sites of the NS3 proteases of HCV-1b and 4a in relation to their catalytic activity and drug susceptibility. Here, we improved the methodology, extended the analysis to include genotype 3a (predominant in South Asia including Pakistan), and compared the results of the three genotypes (1b, 3a and 4a). The 4D analyses of the interactions between the catalytic triad residues (His57, Asp81, and Ser139) indicate conformational instability of the catalytic site in HCV-3a and 4a compared to that of HCV-1b NS3 protease. The divergence is gradual and genotype-dependent, with HCV-1b being the most stable, HCV-4a being the most unstable and HCV-3a representing an intermediate state. These results suggest that the structural dynamics behavior, more than the rigid structure, could be related to the altered catalytic activity and drug susceptibility seen in NS3 proteases of HCV-3a and 4a.

HIV/hepatitis C virus coinfection management: changing guidelines and changing paradigms

OBJECTIVES

The aim of the study was to consider the impact of new direct-acting antiviral (DAA) regimens on hepatitis C virus (HCV) treatment in HIV/HCV coinfection.

METHODS

Current coinfection guidelines were reviewed and the impact of recent DAA publications evaluating HIV-coinfected individuals was considered.

RESULTS

Current coinfection guidelines recommend HIV antiretroviral therapy initiation prior to HCV antiviral therapy. New all-oral, combination antiviral therapy composed of one or more DAAs with or without ribavirin will change this paradigm. As these regimens are better tolerated, it will be possible to offer nearly all HCV-infected patients antiviral therapy, including those with HIV infection. All-oral regimens may impact the incidence of HCV infection by providing a treatment option that can be safely and broadly utilized in high-risk populations with the benefits of curing individual patients and addressing broader public health concerns related to HCV.

CONCLUSIONS

HCV infection treatment should no longer be a secondary consideration restricted to the minority of HIV/HCV-coinfected patients.

Will there be a vaccine to prevent HCV infection?

Prevention of hepatitis C virus (HCV) infection by vaccination has been a priority since discovery of the virus and the need has not diminished over the past 25 years. Infection rates are increasing in developed countries because of intravenous drug use. Reducing transmission will be difficult without a vaccine to prevent persistence of primary infections, and also secondary infections that may occur after cure of chronic hepatitis C with increasingly effective direct-acting antiviral (DAA) regimens. Vaccine need is also acute in resource poor countries where most new infections occur and DAAs may be unaffordable. Spontaneous resolution of HCV infection confers durable protection, but mechanisms of immunity remain obscure and contested in the context of vaccine design. A vaccine must elicit a CD4+ helper T cell response that does not fail during acute infection. The need for neutralizing antibodies versus cytotoxic CD8+ T cells is unsettled and reflected in the design of two very different vaccines evaluated in humans for safety and immunogenicity. Here we review the status of vaccine development and the scientific and practical challenges that must be met if the burden of liver disease caused by HCV is to be reduced or eliminated.