In 2019, the Ward 86 outpatient HIV clinic at San Francisco General Hospital implemented POP-UP to improve health outcomes among the homeless and unstably housed population with HIV. POP-UP provides low-barrier comprehensive HIV primary care, substance use services, mental health services, and case management to this population with the goal of retaining clients in care and improving viral suppression. Among POP-UP participants, 44% who were unstably housed and not virally suppressed at the start of the study were virally suppressed 12 months after enrollment.

San Francisco, CA

Implementation Guide
Evidence-informed intervention
Evidence-informed intervention
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Clinical service delivery model
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Retention in HIV medical care; Viral suppression
Icon for Focus Population
People who are unstably housed
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Hospital or hospital-based clinic
Need Addressed

The homeless and unstably housed population generally experiences poorer health outcomes than the overall population with HIV.1 In San Francisco, only 27% of this population had reached viral suppression in 2021 compared to 75% of those who were housed.2 While some care models have achieved success for similar populations, they do not address the unique comorbidities, including substance use and mental health disorders, and health-related social needs of the homeless and unstably housed population, including  basic subsistence needs and lack of health care coverage. POP-UP aims to improve service utilization and viral suppression for homeless and unstably housed people through a care model that addresses these unique needs.

“The POP-UP low-barrier, clinic-based HIV primary care model is a promising approach to improving care engagement and HIV viral suppression among [people] with overlapping barriers to care engagement, including homelessness or unstable housing, substance use, and mental health diagnoses.”

Core Elements
Low-barrier primary and HIV care

POP-UP is open to clients for walk-in appointments on weekday afternoons; clients can access comprehensive primary care services, same-day antiretroviral therapy (ART), substance use services, mental health services, social services, and onsite laboratory services. This walk-in model allows Ward 86 clinic staff, including a social worker, nurse, and small group of clinicians, to better engage with clients who may typically arrive late to appointments or miss appointments altogether in traditional clinical settings. Staff also prioritize building strong relationships with clients to encourage retention in care. 

Medication-assisted treatment (MAT)

POP-UP staff provide medication-assisted treatment (MAT) for substance use disorders, including buprenorphine. Clients can pick up the medication directly from the clinic, removing the need to visit a pharmacy. Clients can receive in-clinic MAT injections, in addition to harm reduction kits and naloxone. Methadone treatment is also available from a separate neighboring clinic.

Financial incentives

To encourage care engagement, POP-UP provides financial incentives and basic hygiene products, food, and clothing as needed. Incentives are provided in the form of gift cards; clients receive $10 a week per visit with a social worker or clinician; $10 for a lab draw; and $20 every three months for reaching or maintaining viral suppression. 

Enhanced outreach

POP-UP also provides enhanced outreach to homeless and unstably housed clients and links them to social services, such as Medicaid enrollment, benefit services, and medical appointment assistance. A POP-UP social worker conducts weekly outreach visits in the community.  A nurse performs wellness checks on POP-UP clients and promotes medication adherence. A POP-UP phone service accepts text messages and calls from clients as well.


In a study conducted from January 2019 through February 2021, POP-UP enrolled 112 clients who were not virally suppressed and faced housing instability. All enrolled clients had a history of substance use disorder, and more than half were street homeless and had a mental illness. Most clients remained engaged in care, two-thirds were virally suppressed at some point during the 12-month study period, and almost half were virally suppressed at the end of the 12 months, compared to none at baseline.

Evaluation data
  • Client enrollment and medical record data
  • Viral suppression at some point during 12 months and at 12 months
  • Care engagement, as measured by an appointment in each of the three four-month periods
  • 66% of clients were virally suppressed at some point during 12 months of participation
  • 44% of clients maintained viral suppression 12 months post-enrollment
  • 70% of clients were engaged in care (at least one appointment in each of the three four-month periods)

Source: Hickey MD, Imbert E, Appa A, et al. HIV treatment outcomes in POP-UP: Drop-in HIV primary care model for people experiencing homelessness. J Infect Dis. 2022;226(Suppl 3):S353–S362.

"HIV patients who are homeless or unstably housed have unique needs that can make it challenging to connect to usual care. POP-UP aims to address these needs." 

Planning & Implementation

Identification of clients. Eligible clients are identified through referrals from Ward 86 clinic staff and other local providers, surveillance data analyzed by the San Francisco Department of Public Health linkage team, and a review of electronic health record data.

Staff training. POP-UP staff participate in in-service clinical training on topics such as substance use disorder treatment, and psychiatric co-morbidities.

Weekly case conferencing. Staff engage in weekly case conferences to coordinate care and discuss client progress. A psychiatrist is available to consult with POP-UP primary care providers on the mental health needs of homeless and unstably housed clients.

Data dashboard. POP-UP leverages a data dashboard that organizes client services and follow-up activities to support care coordination through POP-UP’s extended care team. This data dashboard is used to enhance clinic services, follow-up with clients, and facilitate care team coordination. 


Launched in January 2019, POP-UP is an ongoing program at the Ward 86 clinic with financial support from Gilead Sciences, a National Institutes of Health Ending the HIV Epidemic Supplemental Grant, a National Institute of Allergy and Infectious Diseases training grant, and a University of California San Francisco Benioff Homelessness and Housing Initiative Resource Allocation Program Award.

Lessons Learned
  • While POP-UP provides linkage to low-barrier primary care services, almost half of the clients identified as eligible for POP-UP could not be reached for enrollment. Eligible clients who were identified through HIV surveillance data were the least likely to enroll in POP-UP. Staff training on eligibility criteria leads to successful referrals into POP-UP, primarily from primary care and urgent care clinics.
  • Many POP-UP study participants did not reach viral suppression even with sustained care engagement due to poor medication adherence. POP-UP’s care model attempted to address this barrier through medication pickup in convenient packaging, such as blister packs
  • The POP-UP client population had a mortality rate of 9% over the one-year POP-UP evaluation period, which is substantially higher than the overall population with HIV.2 Most client deaths resulted from overdoses from either methamphetamine or methamphetamine and fentanyl combined, which reflects the substance overdose crisis in San Francisco among the homeless and unstably housed population.3
  • POP-UP providers appreciated the support and information offered during weekly case conference meetings and psychologist-led quarterly team sessions, along with feedback from the POP-UP data dashboard reviewed during the weekly case conference meetings.
University of California San Francisco
Elizabeth Imbert, MD, MPH
Associate Professor, Medicine

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