Roussos S, Tsirogianni E, Goulis I, Kalamitsis G, Hatzakis A, Sypsa V.
Population size estimation of people who inject drugs using capture-recapture analysis of multiple respondent-driven sampling rounds: Implications for HIV/HCV burden and harm reduction service planning in Thessaloniki, Greece. Int J Drug Policy. 2025;147:105078.
AbstractBACKGROUND: Accurate population size estimation of people who inject drugs (PWID) is essential for evidence-based drug policy and service planning, yet it remains challenging. An emerging HIV outbreak in Thessaloniki, Greece's second-largest city, highlighted the urgent need for evidence-based population size estimates. METHODS: We applied capture-recapture analysis to five respondent-driven sampling (RDS) rounds conducted during 2019-2021 to estimate PWID population size in Thessaloniki for the 2019-2021 period. These RDS rounds were part of a community-based program aimed at increasing HIV/HCV testing and linkage to care among PWID. We treated each RDS round as a capture source and used log-linear models to estimate PWID population size (past 12 months and past 30 days), accounting for potential dependencies between rounds through interaction terms. We then estimated HIV/HCV disease burden and assessed prevention and harm reduction service coverage against international standards (HIV testing, OAT, NSP). RESULTS: Based on data from 1093 unique participants across five rounds (53.9% currently injecting, 20.3% currently in OAT), capture-recapture analysis estimated 1512 PWID (95% confidence interval (CI): 1345-1741) who had injected drugs in the past 12 months. The estimated prevalence of injecting drug use was 0.22% (95% CI: 0.20-0.25) among adults aged 18-64 years. We estimated 106 people living with HIV (95% uncertainty interval (UI): 83-130) and 945 HCV-antibody-positive individuals (95% UI: 815-1077) among PWID. Needle and syringe program coverage was 36 (95% CI: 31-40) syringes per PWID in 2021. CONCLUSION: Based on this community-based population size estimate, the prevalence of injection was nearly double the official national Greek average. The annual distribution of syringes should increase by 5.6 times to reach the WHO target (≥200 syringes/PWID/year). These findings demonstrate how community-based programs with multiple RDS rounds can also yield population estimates essential for evidence-based drug policy interventions.
Roussos S, Protopapas K, Mastrogianni E, Totsikas C, Moschopoulos CD, Bourmpoutelis S, Resta P, Procter K, Kokolesis E, Antoniadou A, et al. Rapid ART Initiation with BIC/FTC/TAF in People Who Inject Drugs in Greece: Results from a Pilot Single-Arm Study of an Integrated Care Model. Microorganism. 2025;13.
AbstractPeople who inject drugs (PWIDs) remain underserved in HIV care. Evidence on rapid antiretroviral therapy (ART) for PWID is limited. We evaluated feasibility, effectiveness, safety, and patient-reported outcomes (PROs) for rapid initiation of bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) supported by a peer navigation in Greece. This is a single-arm, multicenter pilot study including PWIDs (≥18 years) newly diagnosed or relinking after >3 months off ART. Participants started BIC/FTC/TAF on the same day or within 7 days and received peer navigation for 48 weeks. Co-primary endpoints were Week-24 virologic suppression (HIV-1 RNA < 50 copies/mL; FDA Snapshot) and grade 3-4 adverse events (AEs). Secondary endpoints included complete-case suppression at Weeks 24/48, CD4 recovery, retention, and PROs. Outcomes were compared with historical controls from the same centers. Thirty-seven participants were enrolled (83.8% male; median age 33.3 years). Median time to ART was 0 days (vs 78 in controls, p < 0.001). Retention was 67.6% at Week 24 and 54.1% at Week 48. In the primary (FDA Snapshot) analysis, suppression was 62.2% and 54.1% at Weeks 24 and 48; in complete-case analyses, results were 92.0% and 100%, respectively. Mean CD4 count increased by 208 cells/μL (95% CI 141-275) at Week 48. Quality of life improved and symptom burden decreased. No grade 3-4 AEs occurred. Rapid BIC/FTC/TAF with peer navigation eliminated delays to ART and achieved favorable virologic, immunologic, and PROs among those retained, with good tolerability. Despite retention challenges, this model appears feasible for PWID and may help close HIV care gaps toward UNAIDS 95-95-95 targets.
Boundi S, Roussos S, Sypsa V.
Causes of death among people living in prison in Greece: A 9-year retrospective study (2010-2018) at the national prison hospital. Med Sci Law. 2025:258024251363671.
AbstractPeople living in prisons have higher mortality rates compared to the general population. We undertook a retrospective analysis of deaths recorded between 2010 and 2018 at the sole prison hospital in Greece (Korydallos Prison Special Health Centre for men) to assess the causes of death overall and by type of offence (drug-related or other), sociodemographic characteristics by cause of death, and mortality trends over time. Permission to access forensic reports and criminal files was obtained from the relevant authorities. Deaths were categorized as either non-natural (drug overdose, suicide, and homicide) or natural (cardiovascular disease, cancer, and others). Between 2010 and 2018, 236 deaths were reported; 80.9% were natural deaths, and 19.1% were non-natural deaths. The primary causes of death were circulatory disease (34.7%), cancer (17.8%), suicide (10.2%), respiratory disease (8.9%), and overdose (6.4%). Suicide and overdose accounted for 53.3% and 33.3% of non-natural deaths, respectively. The mean (SD) age at death was 52.4 (16.2) years, with individuals experiencing non-natural deaths being significantly younger than those experiencing natural deaths [39.1 (10.5) vs. 55.5 (15.7), p < 0.001]. Among individuals incarcerated for drug-related offences, 23.8% died from non-natural causes, with drug overdose accounting for 60% of non-natural deaths. A significant peak in mortality was observed in 2013. This study emphasizes the need to closely monitor mortality rates, including drug-related fatalities, to implement suicide prevention training as well as measures to prevent deaths by overdose, including comprehensive harm reduction strategies, overdose education, and naloxone training.
Kostaki EG, Papadimitriou E, Chatzopoulou F, Roussos S, Tsirogianni E, Psichogiou M, Goulis I, Kalamitsis G, Kefala AM, Skoura L, et al. Molecular investigation of a new HIV-1 outbreak among people who inject drugs in Greece: evidence for a dense network of HIV-1 transmission. Sex Transm Infect. 2025.
AbstractOBJECTIVES: Αn HIV-1 outbreak was identified among people who inject drugs (PWID) in Thessaloniki, Greece, during 2019-2021. We aimed to investigate the characteristics of this outbreak by means of molecular epidemiology. METHODS: We analysed 57 sequences from PWID sampled in Thessaloniki during 2019-2023. Phylogenetic trees were inferred using all subtype A sequences from PWID sampled since 1999 in Greece and reference sequences (n=4824). Phylodynamic analysis was performed using the Bayesian birth-death skyline serial model. RESULTS: Most of the 57 study sequences belonged to sub-subtypes A6 (49, 86%) and A1 (4, 7%). Phylogenetic analysis revealed that two (50%) A1 sequences clustered together and 47 (95.9%) A6 sequences fell within three PWID-specific phylogenetic clusters. The 99.6% and 77.9% of pairwise genetic distances within the largest and second largest PWID clusters were lower than 0.015 substitutions/site. Using a more stringent threshold (0.0015 substitutions/site), we identified five networks of sequences from PWID infected within 1 year. The effective reproduction number (R(e)) started to increase at the beginning of 2019 and remained high almost until the end of 2021. The estimated time from HIV-1 infection to diagnosis showed an increasing trend during 2020-2023 (p<0.001). CONCLUSIONS: The regional clustering of the PWID sequences and their low genetic divergence confirm its local spreading and the recent nature of the outbreak. Using a stringent genetic distance threshold, we showed that HIV-1 transmission occurred among large groups of PWID. The time of epidemic growth coincided with the time of the initial identification, and HIV-1 transmission continued at high rates until 2021.
Sperle I, Seyler T, Pericoli F, Duffel E, Hutchinson S, Jauffret-Roustide M, Kåberg M, Ķīvīte-Urtāne A, Seguin-Devaux C, Sypsa V, et al. Standardising monitoring data on drug-related infectious diseases among people who inject drugs in Europe – an update of the European Union Drugs Agency technical protocol, 2024. Euro Surveill. [Internet]. 2025;30(30)::pii=2500007.
Publisher's Version Polaris Observatory Collaborators.
Number of people treated for hepatitis C virus infection in 2014-2023 and applicable lessons for new HBV and HDV therapies. J Hepatol. 2025.
AbstractBACKGROUND & AIMS: The year 2023 marked the 10-year anniversary of the launch of direct-acting antivirals (DAAs) for the treatment of hepatitis C virus (HCV). Monitoring HCV treatment trends by country, region, and globally is important to assess progress toward the World Health Organization's 2030 elimination targets. Additionally, the historical patterns can help predict the treatment uptake for future therapies for other liver diseases. METHODS: The number of people living with HCV (PLHCV) treated between 2014-2023 across 119 countries was estimated using national HCV registries, reported DAA sales data, pharmaceutical companies' reports, and estimates provided by national experts. For the countries with no available data, the average estimate of the corresponding Global Burden of Disease region was used. RESULTS: An estimated 13,816,000 (95% uncertainty intervals: 13,221,000-16,415,000) PLHCV were treated, of whom 12,748,000 (12,226,000-15,231,000) were treated with DAAs, of which 11,081,000 (10,542,000-13,338,000) were sofosbuvir-based DAA regimens. Country-level data accounted for 97% of these estimates. In high-income countries, there was a 41% drop in treatment from its peak, and reimbursement was a large predictor of treatment. In low- and middle-income countries, price played an important role in expanding treatment access through the public and private markets, and treatment continues to increase slowly after a sharp drop at the end of the Egyptian national program. CONCLUSIONS: In the last 10 years, 21% of all HCV infections were treated with DAAs. Regional and temporal variations highlight the importance of active screening strategies. Without program enhancements, the number of treated PLHCV stalled in every country/region, which may not reflect a lower prevalence but may instead reflect the diminishing returns of existing strategies. IMPACT AND IMPLICATIONS: Long-term hepatitis C virus (HCV) infection can lead to cirrhosis and liver cancer. Since 2014, these infections can be effectively treated with 8-12 weeks of oral therapies. In 2015, the World Health Organization established targets to eliminate HCV by 2030, which included treatment targets for member countries. The current study examines HCV treatment patterns across 119 countries and regions from 2014 to 2023 to assess the impact of national programs. This study can assist physicians and policymakers in understanding treatment patterns within similar regions or income groups and in utilizing historical data to refine their strategies in the future.
Papalamprakopoulou Z, Roussos S, Ntagianta E, Triantafyllou V, Kalamitsis G, Dharia A, Sypsa V, Hatzakis A, Talal AH.
Considerations for equitable distribution of digital healthcare for people who use drugs. BMC Health Services Research. 2025;25:531.
AbstractTelehealth holds the potential to expand healthcare access for people who use drugs (PWUD). However, limited data exist on their digital infrastructure access, a prerequisite for telehealth participation. We studied digital healthcare accessibility among PWUD.