Two Drug Epidemics in St. Petersburg, Russia? Substance Use, Risk Behaviors, and HIV and HCV Prevalence Among Young and Older People Who Inject Drugs Attending a Harm Reduction Facility.

Russia has an estimated 1.3-1.8 million people who inject drugs (PWID). In recent years concomitant decline of opioid use and rise of new psychoactive substances (NPS) use was observed. We conducted secondary analysis of survey data collected in 2019-2021 by a harm reduction organization in Saint-Petersburg, Russia (n = 978). Older PWID group (30+) was significantly more likely to use opioids (87.5% vs. 32.4%) than young PWID; young PWID used NPS four times more frequently than older ones (79.9% vs. 21.5%). The odds ratio of being an exclusive stimulant user but not an opioid user among younger cohorts is more than forty-five times higher than among older cohorts all else being equal (AOR = 47.38; 95% CI 21.90-102.53; p < 0.001). The younger respondents were more than four times less likely to be HIV-positive than older participants (8.4% vs. 36.7%) and more than three times less likely to be HCV-positive (23.5% vs. 80.6%). Young PWID were significantly more prone to risk behaviors (syringes sharing in past month; having overdose in the last 12 months; and inconsistent condom use during past 3 months) than older PWID, which renders them vulnerable to rapid HIV and HCV transmission both by parenteral and sexual routes. It is possible that currently we are observing two epidemics- an "old" opioid epidemic among older generations of PWID and a new synthetic cathinones epidemic among younger generations of PWID. New forms of harm reduction tailored to the needs of NPS users along with expansion of existing harm reduction programs for opioid users are urgently needed.