Needle and syringe coverage per injection and factors associated with needle sharing among clients of the Stockholm Needle and Syringe Program, 2013–2023

BACKGROUND: Needle and Syringe Programs (NSP) are a cornerstone of harm reduction, yet evidence on whether they adequately meet injection-related needs and reduce needle sharing in real-world settings, particularly where NSP were introduced late, remains limited. We examined needles to injection coverage and predictors of needle sharing among clients of the Stockholm NSP between 2013 and 2023. METHODS: Using data from a national clinical monitoring system, baseline and repeated follow-up surveys were linked to service data. Injection coverage was assessed by comparing self-reported injection frequency with sterile needles received. Predictors of needle sharing were analyzed using random-effects Poisson regression, reporting adjusted prevalence ratios (aPRs). RESULTS: A total of 4423 NSP clients were included. Average injection coverage increased steadily over time, reaching the WHO target of 300 needles/syringes per person who injects drugs per year from 2019 onward. Most clients received more than one sterile needle per reported injection. Compared with 2013, the adjusted prevalence of needle sharing was 64% lower in 2023 (aPR 0.36; 95% CI: 0.22-0.60). Higher prevalence of sharing was observed among younger clients, women, those with unstable housing, higher injection frequency, stimulant use, and those outside the labor force, while older age and HIV-positive status were associated with lower prevalence. CONCLUSIONS: In a setting with restrictive NSP regulations, sustained improvements in injection coverage and marked reductions in needle sharing were observed over a decade. Persistent disparities among socially vulnerable groups indicate that high overall coverage alone is insufficient and highlight the need for targeted harm-reduction strategies.