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Background and Aims: The human immunodeficiency virus (HIV) outbreak among people who inject drugs (PWID) in Athens, Greece in 2011–13 was the largest recent epidemic in Europe and North America. We aimed to assess trends in HIV prevalence, drug use and access to prevention among PWID in Athens to estimate HIV incidence and identify risk factors and to explore HIV‐1 dispersal using molecular methods during 2014–20. Methods: Two community‐based HIV/hepatitis C programmes on PWID were implemented in 2012–13 (n = 3320) and 2018–20 (n = 1635) through consecutive respondent‐driven sampling (RDS) rounds. PWID were uniquely identified among rounds/programmes. We obtained RDS‐weighted HIV prevalence estimates per round for 2018–20 and compared them to 2012–13. We assessed changes in HIV status, behaviours and access to prevention in PWID participating in both periods. We estimated HIV incidence in a cohort of seronegative PWID as the number of HIV seroconversions/100 person‐years during 2014–20 and used Cox regression to identify associated risk factors. Molecular sequencing and phylogenetic analysis were performed in HIV seroconverters. Results: HIV prevalence per round ranged between 12.0 and 16.2% in 2012–13 and 10.7 and 11.3% in 2018–20 with overlapping 95% confidence intervals (95% CI). Among PWID participating in both programmes, HIV prevalence (95% CI) increased from 14.2% (11.7–17.1%) in 2012–13 to 22.0% (19.0–25.3%) in 2018–20 (P < 0.001). There was a deterioration in socio‐economic characteristics such as homelessness [from 16.2% (95% CI = 13.5–19.2%) to 25.6% (22.3–29.0%)], a shift in cocaine use [16.6% (13.9–19.6%) versus 28.1% (24.7–31.7%], reduced access to free syringes [51.8% (48.0–55.7%) versus 44.5% (40.7–48.3%)] and a decrease in daily injecting [36.2% (32.6–39.9%) versus 28.5% (25.2–32.1%)]. HIV incidence (95% CI) in 2014–20 was 1.94 (1.50–2.52) new cases/100 person‐years and younger age, lower educational level, larger injection network and daily injecting were risk factors. Almost 9% of HIV seroconversions occurred within a newly expanding phylogenetic cluster. Conclusions: In Athens, Greece, compared with the period 2012–13, in the period 2018–20 there was a deterioration in socio‐economic conditions among people who inject drugs, an increase in the use of cocaine, reduced access to needle and syringe programmes and stable low levels of human immunodeficiency virus testing. Ongoing human immunodeficiency virus transmission was documented during 2014–20 in existing as well as new transmission clusters. [ABSTRACT FROM AUTHOR]

Background: During 2011, a dramatic increase (1600%) of reported HIV-1 infections among injecting drug users (IDUs) was noted in Athens, Greece. We herein assess the potential causal pathways associated with this outbreak. Methods: Our study employed high resolution HIV-1 phylogenetic and phylogeographic analyses. We examined also longitudinal data of ecological variables such as the annual growth of gross domestic product (GDP) of Greece in association with HIV-1 and HCV sentinel prevalence in IDUs, unemployment and homelessness rates and HIV transmission networks in Athens IDUs before and during economic recession (2008–2012). Results: IDU isolates sampled in 2011 and 2012 suggested transmission networks in 94.6% and 92.7% of the cases in striking contrast with the sporadic networking (5%) during 1998–2009. The geographic origin of most HIV-1 isolates was consistent with the recently documented migratory waves in Greece. The decline in GDP was inversely correlated with annual prevalence rates of HIV and HCV and with unemployment and homelessness rates in IDUs (all p<0.001). The slope of anti-HCV prevalence in the sentinel populations of IDUs and in “new” drug injectors was found 120 and 1.9-fold (p = 0.007, p = 0.08 respectively) higher in 2008–2012 (economic recession) compared with 2002–2006. The median (25th, 75th) size of transmission networks were 34 (12, 58) and 2 (2, 2) (p = 0.057) in 2008–2012 and 1998–2007, respectively. The coverage of harm reduction services was low throughout the study period. Conclusions: Scaling-up harm reduction services and addressing social and structural factors related to the current economic crisis should be urgently considered in environments where HIV-1 outbreaks may occur. [ABSTRACT FROM AUTHOR]

Background A significant increase in HIV-1 diagnoses was reported among Injecting Drug Users (IDUs) in the Athens (17-fold) and Bucharest (9-fold) metropolitan areas starting 2011. Methods Molecular analyses were conducted on HIV-1 sequences from IDUs comprising 51% and 20% of the diagnosed cases among IDUs during 2011–2013 for Greece and Romania, respectively. Phylodynamic analyses were performed using the newly developed birth–death serial skyline model which allows estimating of important epidemiological parameters, as implemented in BEAST programme. Results Most infections (>90%) occurred within four and three IDU local transmission networks in Athens and Bucharest, respectively. For all Romanian clusters, the viral strains originated from local circulating strains, whereas in Athens, the local strains seeded only two of the four sub-outbreaks. Birth–death skyline plots suggest a more explosive nature for sub-outbreaks in Bucharest than in Athens. In Athens, two sub-outbreaks had been controlled ( Re < 1.0) by 2013 and two appeared to be endemic ( Re ∼ 1). In Bucharest one outbreak continued to expand ( Re > 1.0) and two had been controlled ( Re < 1.0). The lead times were shorter for the outbreak in Athens than in Bucharest. Conclusions Enhanced molecular surveillance proved useful to gain information about the origin, causal pathways, dispersal patterns and transmission dynamics of the outbreaks that can be useful in a public health setting. [ABSTRACT FROM AUTHOR]