Heroin, Fentanyl, Intentional Fentanyl Use and HIV Transmission in a Community-Recruited Sample of Persons Who Inject Drugs, New York City: 2021-2023.

We examined drug use patterns and HIV transmission among persons who inject drugs (PWID) in New York City from 2021 to 2024. Modified respondent-driven sampling was used to recruit PWID from October 2021-February 2024. A structured questionnaire measured demographics, drug use behaviors and overdose experiences (within previous 6 months). Urinalysis was conducted for recent substance use and serum samples were collected for HIV antibody testing. HIV incidence was estimated using a previously published algorithm. We recruited 463 PWID; high percentages of participants reported problematic life circumstances including unstable housing (45%), food insecurity (67%) and drug use problems: 25% reported a recent non-fatal overdose and 55% daily injecting. Fentanyl use was detected in 86% of urinalyses, heroin in 67%, cocaine in 78%, heroin without fentanyl in 1%, and fentanyl and cocaine in 69%. A moderate number of PWID (24%) reported intentional fentanyl use, which was associated with increased food insecurity, unstable housing, injection frequency, cocaine use, and recent non-fatal overdoses and recent receptive syringe sharing. HIV seroprevalence was 6%; there were three likely seroconversions in 1052 total person-years at risk (PYAR) from March 2020 to the times of interviews; estimated HIV incidence rate was 0.19/100 PYAR, 95% CI 0.12-1.67. Despite the increased HIV risks associated with intentional fentanyl use, HIV transmission among PWID has remained low, comparable to pre-fentanyl and pre-COVID-19 levels. Continued monitoring of drug use patterns and increased services for intentional fentanyl use are needed.