The Boston Health Care for the Homeless Program (BHCHP) operates a program providing oral pre-exposure prophylaxis (PrEP) to homeless-experienced people who use drugs who are at high risk of HIV transmission. The BHCHP oral PrEP program uses a low-threshold approach with a harm reduction orientation that supports PrEP prescription initiation and continuation by providing enhanced and flexible health systems navigation, support services and street-based outreach. In a recent study, 16.5% of study participants filled one PrEP prescription (i.e., initiated PrEP), 54.8% filled more than one PrEP prescription (i.e., maintained PrEP) and 28.7% filled zero PrEP prescriptions. Participants who reported injection drug use within the past month had a 2.88 times higher odds of filling one PrEP prescription versus none.
Program description
The oral PrEP program is designed for people who inject drugs and who are currently experiencing or who have experienced homelessness (homeless-experienced). The program supports PrEP initiation efforts by directly tailoring services to homeless-experienced people through street-based outreach oriented to low-barrier harm reduction, flexible health systems navigation and accessible support services.
To be eligible for the PrEP program, participants must be HIV-negative and report sexual and/or substance use behaviours associated with increased risk for HIV transmission (e.g., transactional sex, condomless sex, syringe and/or other drug equipment sharing). Eligible participants are referred to the PrEP program by HIV counsellors, clinicians or staff from local partner organizations (e.g., shelters, local syringe service programs). The PrEP program combines strategies of intensive yet flexible health system navigation services including:
- phone and street-based outreach (e.g., blood tests and medication provision)
- appointment accompaniment
- longer prescription times (ranging between one and 30 days)
- a rapid-start approach to PrEP delivery
- same-day co-located substance use treatment services
- outreach-based blood testing and care coordination with clinic-based teams
Street-based harm reduction nurses provided mobile and secure medication storage, witnessed (observed) medication dosing options and hand delivered PrEP medications seven days per week in high-density areas of homelessness and injection drug use. BCHCP’s pharmacy staff offered flexible PrEP prescriptions (e.g., seven-day pill bottles) that participants could more easily replace if their medication was lost or stolen. Pharmacy staff did not penalize participants for missed appointments or ongoing substance use and offered a weeklong window to provide confirmatory HIV test results to maintain participation in follow-up PrEP care.
BHCHP’s co-located office-based substance use treatment services offered same-day access to opioid agonist treatment (OAT) that supported, engaged and retained participants with opioid use disorder (OUD). By providing same-day access to both PrEP and OAT, the program streamlined access and avoided the need for multiple PrEP-specific follow-up appointments.
Results
Between April 2018 and March 2022, 509 HIV-negative participants were enrolled in BHCHP’s oral PrEP program and were followed for 60 days. To capture the full PrEP cascade of care, the study required a minimum follow-up period of 60 days to allow time for participants to receive more than one PrEP prescription. Among participants:
- the average age was 38 years
- 66.8% identified as cisgender men, 28.3% as cisgender women and 4.9% as transgender or nonbinary
- 60.1% identified as White, 19.3% as Black and 20.6% as another race
- 45.2% identified as straight, 3.7% identified as gay or lesbian, 4.3% identified as bisexual or other and 46.8% did not disclose their sexual orientation
- 91.9% were currently experiencing homelessness; 51.3% of these individuals were staying at shelters and 40.7% were unsheltered
Of the 509 participants in the study:
- 78.4% reported injection drug use within the past month
- 40.1% reported sexual behaviours associated with HIV transmission within the past month
- 70.5% reported at least one mental health disorder diagnosis including generalized anxiety disorder (GAD) (41.7%), depressive disorder (39.7%), post-traumatic stress disorder (22.0%), bipolar disorder (13.9%) and schizophrenia (2.6%)
- 76.8% reported at least one substance use disorder (SUD) diagnosis such as OUD (69.2%), stimulant use disorder (30.6%) and alcohol use disorder (18.3%)
Overall, 146 (28.7%) participants did not fill a PrEP prescription, 84 (16.5%) filled one prescription and 279 (54.8%) filled more than one PrEP prescription.
After adjusting for factors like age and insurance status, participants who had injected drugs in the past month had 2.88 times higher odds of filling one PrEP prescription compared with those who had not recently injected drugs. Compared with participants who did not report GAD, OUD or SUD, those with GAD, OUD and any SUD all had higher odds of filling one PrEP prescription versus none (1.96, 1.94 and 3.09 respectively). Participants with bipolar disorder had 73.0% lower odds of filling one PrEP prescription compared with those without bipolar disorder.
After adjusting for multiple factors, participants who had injected drugs in the past month, had GAD, had OUD or had any SUD all had higher odds of filling multiple PrEP prescriptions versus none compared with their counterparts (3.60, 1.84, 1.83 and 1.96, respectively). Sociodemographic characteristics, sexual behaviours and other mental health disorders were not associated with study outcomes.
What does this mean for service providers?
Findings highlight the potential of low-threshold PrEP programs that have a harm reduction orientation to increase oral PrEP initiation and continuation among homeless-experienced people who use drugs. By providing intensive yet flexible health systems navigation, street-based outreach, interdisciplinary and community-based collaboration and co-located same-day access to oral PrEP and OAT, service providers can effectively offer initial and continued PrEP prescriptions to marginalized individuals who are at risk for HIV.
Offering prescription flexibility and other medication maintenance plans may help participants to continually receive PrEP and mitigate common medication adherence challenges (e.g., medication loss, missed appointments). Co-locating substance use treatment (e.g., OAT) and mental health services for people with bipolar and schizophrenia may further facilitate PrEP initiation and maintenance among these participants.
Related resources
CATIE statement on the use of HIV pre-exposure prophylaxis (PrEP) among people who use drugs – CATIE statement
Using the PrEP cascade to examine PrEP engagement among people who inject drugs – CATIE Prevention in Focus article
Pilot project integrates HIV pre-exposure prophylaxis (PrEP) with harm reduction – CATIE News article
Reference
Eger WH, Shaw LC, Biello KB et al. HIV pre-exposure prophylaxis prescription initiation and maintenance among homeless-experienced people who use drugs. Journal of Acquired Immune Deficiency Syndromes. 2025;98(3):234-241. Available from: https://doi.org/10.1097/QAI.0000000000003568