Through the proposed Substance Checking Outreach and Pre-Exposure Prophylaxis (PrEP) Engagement (SCOPE) study, the investigators will design and evaluate an overdose prevention and HIV prevention study among people who use drugs (PWUD). Specifically, SCOPE will provide access to drug-checking services for PWUD to better understand the contents of the drug supply, in combination with PrEP for those who are HIV-, to both reduce overdose and HIV among PWUD in Baltimore City.

specific study aims are:

1. To prepare the drug-checking technology for deployment in the community through a three-phase process.

   1. To calibrate drug-checking technology through testing samples of illicit substances on the Bruker Alpha obtained from the Baltimore Police crime lab (N=335) and those obtained through the SPARC outreach sessions (N=100).
   2. To validate the drug-checking technology, measuring sensitivity and specificity in detecting illicit substances of public health relevance, by testing samples obtained through partnerships through Baltimore-based harm reduction organizations and comparing findings to the gold standard (laboratory testing).
   3. To pilot the study Bruker Alpha Fourier Transform Infrared Spectroscopy (FT-IR) drug checking machine among People who use drugs (PWUD) (N=20).

2. To develop a community-level, mobile, integrated drug checking and PrEP intervention aimed to increase PWUD engagement in the PrEP care continuum and reduce the burden of overdose.

3. To recruit a longitudinal cohort of people who use drugs (N=500) and follow-up at 6-month intervals for 18 months.

4. To implement the intervention and evaluate its impact on engagement in PrEP care (primary outcome) and overdose prevention among PWUD.

   a. To determine the incremental cost-effectiveness of the intervention in terms of HIV cases averted among PWUD.

5. To assess changes in drug-related wounds among N=100 PWUD in Baltimore who receive wound care services on the intervention van.

   1. To assess changes in drug-related wounds specifically attributed to xylazine.

The initial non-human subjects research plan focused on Aim's 1 drug checking machine calibration among samples procured from the Baltimore Police Forensics Lab tested in Dr. William Clarke's lab and from individuals interacting with SPARC staff during the outreach which occurs 3-4 times per week. These activities are referred to as "Phase 1" throughout this research plan. Based on emerging best practices and in consultation with other drug checking initiatives nationwide, the investigators have now expanded Aim 1 of the study to include three steps needed to prepare the machine for deployment in the field: The first (1a) was calibration of the machine to the local drug supply, as described above; the second (1b) which the investigators are adding in this amendment is an additional validation of the machine's functionality and comparison with gold standard technology; and the third (1c) is piloting the machine with 20 PWUD prior to rolling it out citywide.

Inclusion Criteria:

• 18 years or older,

• self-reports having used illicit stimulants or opioids at least once in the past 3 months,

• self-reports being HIV negative

• reports injection drug use in the past 6 months OR reports at least one of the following indicators of sexual HIV risk exposure in the past 6 months:

  1. Sexually Transmitted Infection (STI) diagnosis in the past 6 months
  2. "Condom-less" vaginal or anal sex in the past 6 months

• Willing to provide a urine sample for urine drug screening of substances

• Willing to undergo rapid HIV testing

• Willing to undergo STI testing

Exclusion Criteria:

• Determined to be too high or drunk or cognitively impaired, less than 18 years of age
• unwilling to provide all required biological specimens (Phase 3 only)
• unwilling/unable to give consent

Project de-identified IPD will made available for published analyses upon request. The investigators will also include the study protocol (IPD supporting information).

The time frame is for the project's IPD/supporting information is 'Unending'; the investigators will consider requests for data related to the project up to five years after publication.

To access project IPD and supporting information, the investigators will consider requests for data from other researchers (university or governmental). The PI will review all requests, approve, and provide IPD access when appropriate.