The study design was changed and this clinical trial will not be conducted.

People who inject drugs (PWID) experience high risk of HIV acquisition. Antiretroviral pre-exposure prophylaxis (PrEP) is an efficacious biomedical HIV prevention strategy for high risk HIV-uninfected individuals including PWID, yet uptake has been low in this population and uptake and adherence interventions have not been developed or tested. Drawing from formative qualitative research, the overall goal of this project is to develop an intervention to promote PrEP uptake and adherence among PWID in the U.S. Northeast. The investigators will:

• Analyze existing literature and data to identify specific barriers and facilitators to PrEP uptake and adherence among PWID to inform the initial adaptation of existing theory-based interventions;
• Conduct qualitative interviews with ~30 PWID and ~10 key informants (PrEP and other clinical and social service providers) to identify intervention targets;
• Develop and iteratively refine and finalize an intervention manual based on feedback from qualitative exit-interviews with an interventionist and ~10 PWID; and
• Conduct a pilot randomized clinical trial (RCT) in ~50 HIV-uninfected PWID to compare PrEP uptake and adherence outcomes and assess intervention feasibility and acceptability.

This mixed methods phased research will use qualitative and quantitative techniques to improve PrEP uptake and adherence among PWID through the following three phases:

• Phase 1 will identify the modifiable determinants of PrEP uptake and adherence among HIV-uninfected PWID using in-depth qualitative interviews with PWID and key informants (KIs). Qualitative interviews will explore perceived acceptability and identify barriers and facilitators to PrEP uptake and adherence among ~30 HIV-uninfected PWID and explore perspectives on optimal PrEP delivery methods with ~15 KIs (e.g., PrEP physicians, community-based organization staff members with experience working with PWID).
• Phase 2 will involve identifying intervention targets and adapting existing intervention strategies to improve PrEP uptake and adherence among PWID. This will involve reviewing the literature to identify and select components of existing, evidence-based medication adherence interventions to adapt for the unique determinants of PrEP uptake and adherence among PWID. Investigators will then develop and iteratively refine and finalize an intervention manual by conducting an open-pilot of the intervention in a community-based setting. Refinements will be based on feedback from qualitative exit-interviews with the interventionist and ~10 PWID.
• Phase 3 will involve pilot testing the resulting PrEP uptake and adherence intervention in a selected community-based setting to obtain preliminary data on PrEP uptake and adherence outcomes (primary outcomes) and intervention feasibility and acceptability (secondary outcomes). Investigators will use a pilot RCT design with a mixed methods process evaluation in which 50 HIV-uninfected PWID will be randomized to the PrEP intervention or a control condition (SEP standard of care; n=25 per arm). Investigators will assess changes in PrEP outcomes (primary outcomes of uptake and adherence) and key implementation measures (e.g., secondary outcomes of acceptability, feasibility, adoption by the interventionist).

For all phases:

Inclusion Criteria:

• An adult PWID
• Self report of any high risk behaviors for HIV (past-month receptive syringe sharing, transactional sex, condomless sex with an HIV-infected or unknown status partner)

Exclusion Criteria:

• Unable or unwilling to provide informed consent

For Phase 3 (the RCT pilot):

Inclusion Criteria:

• Clinically eligible for PrEP (confirmed HIV-uninfected status, adequate renal function [estimated creatinine clearance ≥60 ml/min], and documented hepatitis B virus [HBV] status)