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. - Meylakhs P; Rodionova T; Davitadze A; Lakhov A; Eritsian K; Kislitsyn D; Antonova D; Skochilov R (AIDS and behavior, 2025)