Rapid Assessment Amid an Injection Drug Use-Driven HIV Outbreak in Massachusetts' Merrimack Valley: Highlights from a Case Study.

Illicitly manufactured fentanyl within the drug supply has substantially increased opioid-related overdose deaths and driven infectious disease outbreaks among people who use drugs (PWUD). Local jurisdictions often lack the data and tools necessary to detect and translate such moments into actionable and effective responses. Informed by a risk environment framework, this case study adopted a mixed-methods design spanning two rapid assessment studies with PWUD in Lowell (n = 90) and Lawrence (n = 40), Massachusetts, during an HIV outbreak (2017, Study 1) and following the outbreak (2019, Study 2). Survey responses (n = 130) were summarized by computing descriptive statistics, ethnographic field notes were reviewed, and qualitative interviews (n = 34) were thematically analyzed to contextualize quantitative findings. Study 1 participants reported constrained syringe access, high injecting frequency, syringe reuse, and unsafe syringe disposal practices, and uncovered entrenched social and structural factors exacerbating existing substance use and HIV risks: housing instability, limited harm reduction supplies and services (e.g., MOUD access), and tensions between law enforcement and PWUD. Following the outbreak and substantial local investments in harm reduction and treatment infrastructures, Study 2 participants indicated lower injection risk reporting fewer syringe reuse episodes, improved syringe disposal practices, high frequency of naloxone administration at recent overdoses, frequent testing for HIV and HCV, and greater engagement with syringe services programs. A rapid assessment approach to fentanyl's emergence and a concomitant HIV outbreak provided time-sensitive, critical insights and identified needed and local response strategies. However, unless social and structural risk factors are also addressed, community vulnerability to future HIV outbreaks remains.