A binational cohort of the intersection between substance use, HIV, and associated comorbidities among people who inject drugs in San Diego, CA

University Of California, San Diego, La Jolla CA

Investigators

Abstract

We will prospectively study the intersection between substance use, HIV and related co-morbidities in a cohort of people who use drugs (PWUD) in San Diego County (SD). For >25 years, Strathdee has studied the epidemiology of HIV and related co-infections among PWUD across North America, with N=500-1000 and annual retention ≥90%. Since 2020, our La Frontera I cohort situated on the U.S.-Mexico border has documented the highest HIV and HCV incidence among people who inject drugs in North America. Currently, HIV prevalence among former injectors in SD is 16% compared to 10% among current injectors. Consistent with other U.S. cities, we observed a dramatic shift from injection to non-injection of opiates in recent years, leading us to propose cohort expansion to non-injectors. Due to our location on a major drug trafficking corridor, we observe a wide range of substances (e.g., heroin, fentanyl, methamphetamine, xylazine, benzodiazepines). We previously leveraged La Frontera I to evaluate initiatives to improve uptake of PrEP, COVID-19 testing and vaccination. We propose: 1) To characterize trends and predictors of use of established and emerging drugs, drug use transitions (e.g., shifts from IDU to non-IDU & vice versa) and their impact on HIV incidence and utilization of HIV prevention and treatment. 2) To study prevalence and incidence of the following co-morbidities and their relationship to HIV incidence and utilization of HIV prevention and treatment: i) HCV; ii) STIs (i.e., syphilis, gonorrhea, Chlamydia, MPox), iii) neurobehavioral disturbances. 3) To evaluate the influence of structural interventions on HIV-related risk behaviors and utilization of HIV prevention and treatment including: i) new homelessness policies; ii) drug checking services; iii) vending machines. 4) To contribute to a shared database and biorepositories that serve as a platform for collaborations with end users and community partners. To meet these aims, we will continue to follow PWUD from La Frontera I who are actively using illicit substances, replenishing to arrive at 500 PWID and 500 PWUD (non-injectors) for a total sample of 1000. This will include subgroups vulnerable to HIV in SD (e.g., sex workers, people experiencing homelessness) among whom we expect 52 HIV seroconversions after 5 years of follow-up. Our cohort will include at least 50 PWUD living with HIV who will provide samples for viral load, sequencing and biobanking. All participants will undergo semi-annual interviews and specimen collection. SD is designated as a high priority jurisdiction for the Ending the HIV Epidemic Initiative (EHE) and a high intensity drug trafficking area by the DEA. La Frontera II leverages NIH-funded T32s, the California NeuroHIV Tissue Network, Last Gift Study brain/tissue repositories and the PREPARE Institute which tracks emerging and re-emerging infectious disease threats. Our work is aligned with priorities identified by RFA-DA-25-003, the NIH Office of AIDS Research and the EHE.