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BACKGROUND: People who inject drugs may be at excess risk of acquiring vaccine-preventable diseases and negative associated health outcomes, but experience barriers to vaccination. We aimed to determine vaccination coverage among people who inject drugs globally. METHODOLOGY: We conducted systematic searches of the peer-reviewed and grey literature, date limited from January 2008 to August 2023, focusing on diseases for which people who inject drugs are at elevated risk for and for which an adult vaccination dose is recommended (COVID-19, hepatitis A, hepatitis B, human papillomavirus, influenza, pneumococcal disease, tetanus). To summarise available data, we conducted a narrative synthesis. RESULTS: We included 78 studies/reports comprising 117 estimates of vaccination coverage across 36 countries. Most estimates were obtained from high income countries (80%, n=94). We located estimates for hepatitis B vaccination in 33 countries, which included 18 countries with data on serological evidence of vaccine-derived hepatitis B immunity (range: 6-53%) and 22 countries with self-report data for vaccine uptake (<1-96%). Data for other vaccines were scarcer: reported hepatitis A vaccination coverage ranged 3-89% (five countries), COVID-19 ranged 4-84% (five countries), while we located estimates from fewer than five countries for influenza, tetanus, pneumococcal disease, and human papillomavirus. CONCLUSION: Estimates were sparse but where available indicative of suboptimal vaccination coverage among people who inject drugs. Improving the consistency, timeliness, and geographic coverage of vaccine uptake data among this population is essential to inform efforts to increase uptake.

BACKGROUND: Point-of-care hepatitis C virus (HCV) RNA testing can facilitate single-visit diagnosis and treatment. This study evaluated a single-visit test and treat intervention integrating point-of-care HCV RNA testing, linkage to nursing care, and peer-supported engagement/delivery of treatment among people with recent injecting drug use at a peer-led needle and syringe program (NSP). METHODS: TEMPO Pilot is an interventional cohort study of people with recent injecting drug use (previous month) recruited between September 2019-February 2021 from one peer-led NSP in Sydney, Australia. Participants received point-of-care HCV RNA testing (Xpert HCV Viral Load Fingerstick), linkage to nursing care, and peer-supported engagement/delivery of treatment. The primary endpoint was the proportion initiating HCV therapy. RESULTS: Among 101 people with recent injecting drug use (median age 43; 31% female), 27% (n = 27) were HCV RNA detectable. Treatment uptake was 74% (20 of 27; sofosbuvir/velpatasvir, n = 8; glecaprevir/pibrentasvir, n = 12). Among people initiating treatment (n = 20), 45% (n = 9) initiated treatment at the same visit, 50% (n = 10) in the next 1-2 days, and 5% on day 7 (n = 1). Two participants initiated treatment outside the study (overall treatment uptake 81%). Reasons for not initiating treatment included loss to follow-up (n = 2), no reimbursement (n = 1), not suitable for treatment (mental health) (n = 1), and inability to perform liver disease assessment (n = 1). In the full analysis set, 60% (12 of 20) completed treatment and 40% (8 of 20) had a sustained virological response (SVR). In the evaluable population (excluding people without an SVR test), SVR was 89% (8 of 9). CONCLUSION: Point-of-care HCV RNA testing, linkage to nursing, and peer-supported engagement/delivery led to high HCV treatment uptake (majority single-visit) among people with recent injecting drug use attending a peer-led NSP. The lower proportion of people with SVR highlights the

Background & Aims: Adequate adherence to hepatitis C virus (HCV) treatment is believed to be a key component of treatment success because non-adherence can potentially result in treatment failure and the emergence of resistant viral variants. This analysis assessed factors associated with non-adherence to glecaprevir/pibrentasvir (G/P) therapy and the impact of non-adherence on sustained virological response at post-treatment week 12 (SVR12) rates in HCV genotype (GT) 1-6-infected patients. Methods: Adherence was calculated by pill counts at study visits during treatment, and defined as having a lowest treatment adherence of ≥80% and ≤120% at each study visit. Exploratory logistic regression modelling assessed predictors of non-adherence to G/P therapy. SVR12 rates by treatment adherence were assessed in the intent-to-treat (ITT) population and modified ITT (mITT) population, which excludes non-virological failures. Results: Overall, 97% (2024/2091) of patients were adherent to G/P therapy at all consecutive study visits. Alcohol use was the only baseline characteristic independently associated with non-adherence to G/P therapy (OR: 2.38; 95% CI: 1.13-5.01; P =.022). In the mITT population, overall SVR12 rates were high both in patients who were adherent to G/P therapy and those who were not (99% [1983/2008] and 95% [58/61] respectively; P =.047). Corresponding SVR12 rates in the ITT population were 98% (1983/2024) and 87% (58/67) respectively. Conclusions: Most patients adhered to G/P therapy. SVR12 rates were high both in patients who were adherent to G/P treatment and those who were not. Patient education on treatment adherence should remain an important part of HCV treatment. Clinical trials registration: NCT02604017, NCT02640482, NCT02640157, NCT02636595, NCT02642432, NCT02651194, NCT02243293, NCT02446717.

BACKGROUND: New technologies and therapies allow the possibility of a single-visit test and treat model for hepatitis C virus (HCV), addressing some of the barriers to care faced by people who inject drugs. METHODS: The TEMPO Pilot Study was an interventional cohort study evaluating a single-visit test and treat intervention among people with recent injecting drug use at a one peer-led needle and syringe program (NSP) in Sydney, Australia between September 2019 and February 2021. This analysis evaluated awareness of HCV status and agreement of self-report with HCV RNA test results. The analysis also assessed acceptability of: modality of result delivery, modality of blood sampling, site of treatment, and duration of treatment. RESULTS: Among 101 participants (median age 43; 31% female), 100 had a valid HCV RNA test result and 27% (27/100) were HCV RNA detectable. Overall, 65% (65/100) were aware of their status. Among people with a positive HCV RNA result, 48% (13/27) were aware of their status. People preferred same-day HCV test results (95%, 96/101), and preferred to receive results in person (69%, 70/101). Receiving treatment at an NSP was acceptable (100%, 101/101) and 78% (79/101) were willing to discuss their health with a peer NSP worker. CONCLUSION: Half of people with current HCV infection were aware of their status. The high acceptability of simplified testing and treatment pathways delivered at NSPs indicates that this is an appropriate strategy to improve HCV awareness and treatment uptake in this population.

BACKGROUND & AIMS: Shortened duration therapy for acute and recent HCV infection has been shown to be highly effective in several small non-randomised studies with direct-acting antiviral regimens; however, large randomised studies are lacking. METHODS: REACT was an NIH-funded multicentre international, open-label, randomised, phase IV non-inferiority trial examining the efficacy of short course (6-week) vs. standard course (12-week) therapy with sofosbuvir-velpatasvir for recent HCV infection (estimated duration of infection ≤12 months). Randomisation occurred at week 6. The primary endpoint was sustained virological response 12 weeks after treatment end (SVR12) in the intention-to treat (ITT) population. A total of 250 participants were due to be enrolled, but on advice of the data safety and monitoring board the study was halted early. RESULTS: The primary analysis population consisted of 188 randomised participants at termination of study enrolment; short arm (n = 93), standard arm (n = 95). Ninety-seven percent were male and 69% HIV positive. ITT SVR12 was 76/93, 81.7% (95% CI 72.4-89.0) in the short arm and 86/95, 90.5% (95% CI 82.7-95.6) in the standard arm. The difference between the arms was -8.8 (95% CI -18.6 to 1.0). In modified ITT analysis, wherein non-virological reasons for failure were excluded (death, reinfection, loss to follow-up), SVR12 was 76/85, 89.4% (95% CI 80.8-95.0) in the short arm and 86/88, 97.7% in the standard arm (95% CI 92.0-99.7; difference -8.3%, p = 0.025). CONCLUSIONS: In this randomised study in recent HCV infection, a 6-week course of sofosbuvir-velpatasvir did not meet the criteria for non-inferiority to standard 12-week therapy. LAY SUMMARY: In this randomised trial, 188 people with recently acquired hepatitis C infection were randomly assigned to treatment using either a short 6-week course (93 people) or standard 12-week course (95 people) of the hepatitis C treatment sofosbuvir/velpatasvir. There were 9 cases of relapse af

BACKGROUND AND AIMS: Not all people experiencing opioid dependence benefit from oral opioid agonist treatment. The aim of this study was to examine perceptions of (supervised) injectable opioid agonist treatment (iOAT) (described as 'an opioid similar to heroin self-injected at a clinic several times a day') among people who regularly use opioids and determine how common iOAT eligibility criteria accord with interest in iOAT. DESIGN: Cross-sectional survey SETTING: Sydney, Melbourne and Hobart, Australia PARTICIPANTS: A total of 344 people (63% male) who use opioids regularly and had ever injected opioids, interviewed December 2017-March 2018. The mean age of participants was 41.5 years [standard deviation (SD) = 8.5]. MEASUREMENTS: Primary outcome measures were interest in iOAT, factors associated with interest and the proportion of participants who would be eligible using common criteria from trials and guidelines. We examined willingness to travel for iOAT, medication preferences and perspectives on whom should receive iOAT. FINDINGS: Overall, 53% of participants (n = 182) believed that iOAT would be a good treatment option for them. Participants who believed that iOAT was a good treatment option for them were more likely to be male [adjusted odds ratio (aOR) = 1.76, 95% confidence interval (CI) = 1.10-2.82], have used heroin in the past month (aOR = 6.03, 95% CI = 2.86-12.71), currently regularly inject opioids (aOR = 1.84, 95% CI = 1.16-2.91) and have met ICD-10 criteria for opioid dependence (aOR = 3.46, 95% CI = 1.65-7.24). Those interested in iOAT had commenced more treatment episodes (aOR =1.06, 95% CI = 1.00-1.12). Among those interested in iOAT (n = 182), 26% (n = 48) met common eligibility criteria for iOAT. CONCLUSIONS: Interest in injectable opioid agonist treatment does not appear to be universal among people who regularly use opioids. Among study participants who expressed interest in injectable opioid agonist treatment, most did not meet common elig

Background. We evaluated the impact of opioid substitution therapy (OST) on the completion, adherence, efficacy, and safety of the 3-direct-acting antiviral regimen of ombitasvir, paritaprevir (identified by AbbVie and Enanta) co-dosed with ritonavir, and dasabuvir ± ribavirin among patients infected with hepatitis C virus (HCV) genotype (GT) 1, with or without compensated cirrhosis. Methods. Data were pooled from GT1-infected patients enrolled in 12 phase II/III/IIIb clinical trials and categorized by use of OST. Patients with ongoing drug use were excluded. HCV treatment completion, treatment adherence (≥90%), sustained virologic response at post-treatment week 12 (SVR12), and adverse events were assessed. Results. Of 4747 patients, 3% (n = 149) received OST. Among patients receiving OST vs those not receiving OST, 82% (n = 122) vs 52% (n = 2409) had GT1a infection; 76% (n = 113) vs 61% (n = 2792) were treatment naïve; and 17% (n = 25) vs 18% (n = 830) had cirrhosis, respectively. The proportion of patients completing HCV treatment did not differ between those receiving and not receiving OST (97% [n = 144] vs 98% [n = 4510], respectively), whereas adherence to treatment was reduced in patients receiving vs those not receiving OST (88% [n = 105] vs 97% [n = 4057], respectively). SVR12 was similar between patients receiving and not receiving OST (94% [n = 140] vs 96% [n = 4405], respectively; P = .273). Treatment was well tolerated. Conclusions. Although treatment adherence was lower in patients receiving OST vs those not receiving OST, treatment completion and SVR12 were similar between groups. These data support the use of direct-acting antiviral therapies in patients receiving OST.

Background: While opioid agonist therapy (OAT) reduces the risk of hepatitis C virus (HCV) acquisition among people who inject drugs (PWID), protective effects may be attenuated in females. We used pooled data from an international collaboration of prospective cohorts to assess sex disparities in HCV incidence among PWID exposed to OAT. Methods: Independent predictors of HCV infection were identified using Cox regression models with random effects after accounting for the clustering effect of study sites. Unadjusted and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) are presented in sex-specific analyses. Results: Among 701 participants exposed to OAT, HCV incidence was 16.5/100 person-years of observation (PYO) (95% CI, 13.1-20.7) in females and 7.6/100 PYO (95% CI, 6.0-9.5) in males (female:male adjusted HR [aHR], 1.80 [95% CI, 1.37-2.22]; P <. 001). Factors associated with HCV acquisition among females exposed to OAT included nonwhite race (aHR, 1.79 [95% CI, 1.25-2.56]; P =. 001), unstable housing (aHR, 4.00 [95% CI, 3.62-4.41]; P <. 001), daily or more frequent injection (aHR, 1.45 [95% CI, 1.01-2.08]; P =. 042), and receptive syringe sharing (aHR, 1.43 [95% CI, 1.33-1.53]; P <. 001). Conclusions: Female PWID exposed to OAT are twice as likely as their male counterparts to acquire HCV. While there is a need for better understanding of sex differences in immune function and opioid pharmacokinetic and pharmacodynamic parameters, structural and behavioral interventions that target women are required to bolster the efficacy of OAT in preventing HCV transmission.

Gaps in hepatitis C virus (HCV) testing, diagnosis, liver disease assessment and treatment uptake among people who inject drugs (PWID) persist. We aimed to describe the cascade of HCV care among PWID in Australia, prior to and following unrestricted access to direct-acting antiviral (DAA) treatment. Participants enrolled in an observational cohort study between 2014 and 2018 provided fingerstick whole-blood samples for dried blood spot, Xpert HCV Viral Load and venepuncture samples. Participants underwent transient elastography and clinical assessment by a nurse or general practitioner. Among 839 participants (mean age 43 years), 66% were male (n = 550), 64% (n = 537) injected drugs in the previous month, and 67% (n = 560) reported currently receiving opioid substitution therapy. Overall, 45% (n = 380) had detectable HCV RNA, of whom 23% (n = 86) received HCV treatment within 12 months of enrolment. HCV treatment uptake increased from 2% in the pre-DAA era to 38% in the DAA era. Significant liver fibrosis (F2-F4) was more common in participants with HCV infection (38%) than those without (19%). Age 50 years or older (aOR, 2.88; 95% CI, 1.18-7.04) and attending a clinical follow-up with nurse (aOR, 3.19; 95% CI, 1.61-6.32) or physician (aOR, 11.83; 95% CI, 4.89-28.59) were associated with HCV treatment uptake. Recent injection drug use and unstable housing were not associated with HCV treatment uptake. HCV treatment uptake among PWID has increased markedly in the DAA era. Evaluation of innovative and simplified models of care is required to further enhance treatment uptake.

Introduction Opioid agonist treatment is effective for opioid dependence and newer extended-release buprenorphine (BUP-XR) injections represent a significant development. The Community Long-Acting Buprenorphine (CoLAB) study aims to evaluate client outcomes among people with opioid dependence receiving 48 weeks of BUP-XR treatment, and examines the implementation of BUP-XR in diverse community healthcare settings in Australia. Methods and analysis The CoLAB study is a prospective single-arm, multicentre, open-label trial of monthly BUP-XR injections in people with opioid dependence. Participants are being recruited from a network of general practitioner and specialist drug treatment services located in the states of New South Wales, Victoria and South Australia in Australia. Following a minimum 7 days on 8-32 mg of sublingual buprenorphine (±naloxone), participants will receive monthly subcutaneous BUP-XR injections administered by a healthcare practitioner at intervals of 28 days (-2/+14 days). The primary endpoint is participant retention in treatment at 48 weeks after treatment initiation. Secondary endpoints will evaluate dosing schedule variations, craving, withdrawal, substance use, health and well-being, and client-reported treatment experience. Qualitative and costing substudies will examine implementation barriers and facilitators at the client and provider level. Ethics and dissemination The study has received ethics approval from the St Vincent's Hospital Sydney Human Research Ethics Committee (Ref. HREC/18/SVH/221). The findings will be disseminated via publication in peer-reviewed journals, presentations at national and international scientific conferences, and in relevant community organisation publications and forums. Trial registration number NCT03809143 Protocol identifier CoLAB1801, V.4.0 dated 01 August 2019

Introduction: Over the last two decades, the incidence of hepatitis C virus (HCV) co-infection among men who have sex with men (MSM) living with HIV began increasing in post-industrialized countries. Little is known about transmission of acute or recent HCV, in particular among MSM living with HIV co-infection, which creates uncertainty about potential for reinfection after HCV treatment. Using phylogenetic methods, clinical, epidemiological and molecular data can be combined to better understand transmission patterns. These insights may help identify strategies to reduce reinfection risk, enhancing effectiveness of HCV treatment as prevention strategies. The aim of this study was to identify multi-risk profiles and factors associated with phylogenetic pairs and clusters among people with recent HCV infection. Methods: Data and specimens from five studies of recent HCV in Australia and New Zealand (2004 to 2015) were used. HCV Core-E2 sequences were used to infer maximum likelihood trees. Clusters were identified using 90% bootstrap and 5% genetic distance threshold. Multivariate logistic regression and latent class analyses were performed. Results: Among 237 participants with Core-E2 sequences, 47% were in a pair/cluster. Among HIV/HCV co-infected participants, 60% (74/123) were in a pair/cluster, compared to 30% (34/114) with HCV mono-infection (p < 0.001). HIV/HCV co-infection (vs. HCV mono-infection; adjusted odds ratio (AOR), 2.37, 95% confidence interval (CI), 1.45, 5.15) was independently associated with phylogenetic clustering. Latent class analysis identified three distinct risk profiles: (1) people who inject drugs, (2) HIV-positive gay and bisexual men (GBM) with low probability of injecting drug use (IDU) and (3) GBM with IDU & sexual risk behaviour. Class 2 (vs. Class 1, AOR 3.40; 95% CI, 1.52, 7.60), was independently associated with phylogenetic clustering. Many clusters displayed homogeneous characteristics, such as containing individuals exclusively

Interactions between the host immune system and the viral variants determine persistence of hepatitis C virus (HCV) infection after the acute phase of infection. This study describes the genetic variability of within-host HCV viral variants in acute infection and correlates it with host- and virus-related traits and infection outcome. Next generation sequence data (Illumina, MiSeq platform) of viral genomes from 116 incident acute infections (within 180 days of infection) were analysed to determine all the single nucleotide polymorphism (SNP) frequencies above a threshold of 0.1%. The variability of the SNPs for the full open reading frame of the genome as well as for each protein coding region were compared using mean standardized Shannon entropy (SE) values calculated separately for synonymous and nonsynonymous mutations. The envelope glycoproteins regions (E1 and E2) had the highest SE values (indicating greater variability) followed by the NS5B region. Nonsynonymous mutations rather than synonymous mutations were the main contributors to genomic variability in acute infection. The mean difference of Shannon entropy was also compared between subjects after categorizing the samples according to host and virus-related traits. Host IFNL3 allele CC polymorphism at rs12979860 (vs others) and viral genotype 1a (vs 3a) were associated with higher genomic variability across the viral open reading frame. Time since infection, host gender or continent of origin was not associated with the viral genomic variability. Viral genomic variability did not predict spontaneous clearance.

People who are homeless have increased hepatitis C virus (HCV) infection risk, and are less likely to access primary healthcare. We aimed to evaluate HCV RNA prevalence, liver disease burden, linkage to care and treatment uptake and outcomes among people attending a homelessness service in Sydney. Participants were enrolled in an observational cohort study with recruitment at a homelessness service over eight liver health campaign days. Finger-stick whole-blood samples for Xpert® HCV Viral Load and venepuncture blood samples were collected. Participants completed a self-administered survey and received transient elastography and clinical assessment by a general practitioner or nurse. Clinical follow-up was recommended 2-12 weeks after enrolment. For participants initiating direct-acting antiviral (DAA) therapy, medical records were audited retrospectively and treatment outcome data were collected. Among 202 participants (mean age, 48 years), 82% were male (n = 165), 39% (n = 78) reported ever injecting drugs, of whom 63% (n = 49) injected in the previous month. Overall, 23% (n = 47) had detectable HCV RNA and 6% (n=12) had cirrhosis. HCV RNA prevalence among participants with either injecting or incarceration history was 35% (37/105), compared to 4% (3/73) among participants without these risk factors. Among those with detectable HCV RNA, 23 (49%) commenced therapy, of whom 65% (n = 15) achieved sustained virological response, while the remainder had no available treatment outcome. No participant had documented virological failure. HCV DAA treatment uptake among people attending a homelessness service was encouraging, but innovative models of HCV care are required to improve linkage to care and treatment uptake among this highly marginalized population.

Background: People who inject drugs (PWID) are at an elevated risk of fatal overdose in the first year after experiencing a non-fatal event. Such non-fatal events may also result in overdose-related sequelae, ranging from physical injury to paralysis. Given variation in drug markets and treatment availability across countries and regions, we may see similar variations in non-fatal overdose prevalence. Monitoring non-fatal overdose prevalence among PWID is essential for informing treatment intervention efforts, and thus our review aims to estimate the global, regional, and national prevalence of non-fatal overdose, and determine characteristics associated with experiencing such an event. Methods: We conducted a systematic review and meta-analyses to estimate country, regional, and global estimates of recent and lifetime non-fatal overdose prevalence among PWID. Using meta-regression analyses we also determined associations between sample characteristics and non-fatal overdose prevalence. Results: An estimated 3.2 (1.8–5.2) million PWID have experienced at least one overdose in the previous year. Among PWID, 20.5% (15.0–26.1%) and 41.5% (34.6–48.4%) had experienced a non-fatal event in the previous 12 months and lifetime respectively. Frequent injecting was strongly associated with PWID reporting recent and lifetime non-fatal overdose. Estimates of recent non-fatal overdose were particularly high in Asia and North America. Conclusion: Around one in five PWID are at an elevated risk of fatally overdosing every year, however there is substantial geographical variation. In countries with higher rates of non-fatal overdose there is need to introduce or mainstream overdose prevention strategies such as opioid agonist treatment and naloxone administration training programs.

Subsidized direct-acting antiviral (DAA) treatment recently became available to all adults living with chronic hepatitis C virus (HCV) in Australia. Based on rapid uptake (32 600 people initiated DAA in 2016), we estimated the impact on HCV epidemiology and mortality in Australia and determined if Australia can meet the WHO HCV elimination targets by 2030. Using a mathematical model, we simulated pessimistic, intermediate and optimistic DAA treatment scenarios in Australia over 2016-2030. We assumed treatment and testing rates were initially higher for advanced fibrosis and the same across HCV transmission risk level sub-populations. We also assumed constant testing rates after 2016. We compared the results to the 2015 level and a counterfactual (IFN-based) scenario. During 2016-2030, we estimated an intermediate DAA treatment scenario (2016, 32 600 treated; 2017, 21 370 treated; 2018 17 100 treated; 2019 and beyond, 13 680 treated each year) would avert 40 420 new HCV infections, 13 260 liver-related deaths (15 320 in viraemic; −2060 in cured) and 10 730 HCC cases, equating to a 53%, 63% and 75% reduction, respectively, compared to the IFN-based scenario. The model also estimated that Australia will meet the WHO targets of incidence and treatment by 2028. Time to a 65% reduction in liver-related mortality varied considerably between HCV viraemic only cases (2026) and all cases (2047). Based on a feasible DAA treatment scenario incorporating declining uptake, Australia should meet key WHO HCV elimination targets in 10 to15 years. The pre-DAA escalation in those with advanced liver disease makes the achievement of the liver-related mortality target difficult.

Background & Aims: The World Health Organization (WHO) established targets to eliminate hepatitis C virus (HCV) infection as a public health threat by 2030. Evidence that HCV treatment can lower viraemic prevalence among people who inject drugs (PWID) is limited. Broad accessibility of direct-acting antiviral (DAA) therapy in Australia, since March 2016, provides an opportunity to assess the efficacy of these treatments at a population level in a real-world setting. Methods: Data from Australia's annual bio-behavioural surveillance examined treatment uptake and estimated viraemic prevalence among PWID attending needle syringe programs nationally between 2015 and 2017. Multivariate logistic regression identified variables independently associated with HCV treatment among those considered eligible (anti-HCV positive excluding HCV RNA negative with no self-reported history of HCV treatment) in 2017. Results: Annual samples ranged from 1,995–2,380 PWID. Anti-HCV prevalence declined from 57% (2015) to 49% (2017, χ2 p trend <0.001), with 40–56% of anti-HCV positive respondents providing sufficient sample for HCV RNA testing. Between 2015 and 2017, treatment uptake among those eligible increased from 10% to 41% (χ2 p trend <0.001) and viraemic prevalence among the overall sample declined from 43% to 25% (χ2 p trend <0.001). In multivariable analysis, older age (≥50 years adjusted odds ratio [aOR] 1.82; 95% CI 1.09–3.06;p = 0.023 and 44–49 years aOR 1.75; 95% CI 1.03–3.00;p = 0.038 vs. ≤37 years) and history of opioid substitution therapy (aOR 2.06; 95% CI 1.30–3.26; p = 0.002) were independently associated with treatment. Conclusions: This study confirms PWID are willing to initiate treatment when HCV DAA therapy is available and provides population-level evidence of a decline in viraemic prevalence among people most at risk of ongoing HCV transmission. Scaled up surveillance and monitoring are required to evaluate progress toward WHO HCV elimination goals. Lay summary: Th

Transfer of hepatitis C virus (HCV) infection from a donor to a new recipient is associated with a bottleneck of genetic diversity in the transmitted viral variants. Existing data suggests that one, or very few, variants emerge from this bottleneck to establish the infection (transmitted founder [T/F] variants). In HCV, very few T/F variants have been characterized due to the challenges of obtaining early infection samples and of high throughput viral genome sequencing. This study used a large, acute HCV, deep-sequenced dataset from first viremia samples collected in nine prospective cohorts across four countries, to estimate the prevalence of single T/F viruses, and to identify host and virus-related factors associated with infections initiated by a single T/F variant. The short reads generated by Illumina sequencing were used to reconstruct viral haplotypes with two haplotype reconstruction algorithms. The haplotypes were examined for random mutations (Poisson distribution) and a star-like phylogeny to identify T/F viruses. The findings were cross-validated by haplotype reconstructions across three regions of the genome (Core-E2, NS3, NS5A) to minimize the possibility of spurious overestimation of single T/F variants. Of 190 acute infection samples examined, 54 were very early acute infections (HCV antibody negative, RNA positive), and single transmitted founders were identified in 14 (26%, 95% CI: 16–39%) after cross validation across multiple regions of the genome with two haplotype reconstruction algorithms. The presence of a single T/F virus was not associated with any host or virus-related factors, notably viral genotype or spontaneous clearance. In conclusion, approximately one in four new HCV infections originates from a single T/F virus. Resolution of genomic sequences of single T/F variants is the first step in exploring unique properties of these variants in the infection of host hepatocytes.

BACKGROUND AND AIMS: People who have recently injected drugs are a priority population in efforts to achieve hepatitis C virus (HCV) elimination. This study estimated the prevalence and number of people with recent injecting drug use living with HCV, and the proportion of people with recent injecting drug use among all people living with HCV infection at global, regional and country-levels. METHODS: Data from a global systematic review of injecting drug use and HCV antibody prevalence among people with recent (previous year) injecting drug use were used to estimate the prevalence and number of people with recent injecting drug use living with HCV. These data were combined with a systematic review of global HCV prevalence to estimate the proportion of people with recent injecting drug use among all people living with HCV. RESULTS: There are an estimated 6.1 million [95% uncertainty interval (UI) = 3.4-9.2] people with recent injecting drug use aged 15-64 years living with HCV globally (39.2% viraemic prevalence; UI = 31.6-47.0), with the greatest numbers in East and Southeast Asia (1.5 million, UI = 1.0-2.1), eastern Europe (1.5 million, UI = 0.7-2.4) and North America (1.0 million, UI = 0.4-1.7). People with recent injecting drug use comprise an estimated 8.5% (UI = 4.6-13.1) of all HCV infections globally, with the greatest proportions in North America (30.5%, UI = 11.7-56.7), Latin America (22.0%, UI = 15.3-30.4) and eastern Europe (17.9%, UI = 8.2-30.9). CONCLUSIONS: Although, globally, 39.2% of people with recent injecting drug use are living with hepatitis C virus (HCV) and 8.5% of all HCV infections occur globally among people with recent injecting drug use, there is wide variation among countries and regions.