HIV pre-exposure prophylaxis programmatic preferences among people who inject drugs: findings from a discrete choice experiment.

Background: Pre-exposure prophylaxis (PrEP) holds promise for decreasing new HIV infections among people who inject drugs (PWID), yet daily oral PrEP use is low, and PrEP modality and delivery strategy preferences in this population remain understudied.

Methods: From May 2022-June 2023, we conducted a discrete choice experiment (DCE) with PWID in San Diego, California. Participants viewed 18 PrEP program scenarios in sets of three and chose their preferred scenario within each set.

A mixed methods study to inform fatal overdose prevention in San Diego, California: Perspectives from people who use drugs.

Background: In the United States, community overdose education and naloxone distribution (OEND) programs have demonstrated efficacy in reducing opioid-related mortality. OEND programs have expanded across San Diego County, California, but differential naloxone accessibility among people who use drugs (PWUD) has not been assessed. We examined factors that shape individual naloxone accessibility in San Diego.

Engineered deletions of HIV replicate conditionally to reduce disease in nonhuman primates.

Antiviral therapies with reduced frequencies of administration and high barriers to resistance remain a major goal. For HIV, theories have proposed that viral-deletion variants, which conditionally replicate with a basic reproductive ratio [R] > 1 (termed "therapeutic interfering particles" or "TIPs"), could parasitize wild-type virus to constitute single-administration, escape-resistant antiviral therapies. We report the engineering of a TIP that, in rhesus macaques, reduces viremia of a highly pathogenic model of HIV by >3log following a single intravenous injection.

Illicit Fentanyl Use and Hepatitis C Virus Seroconversion Among People Who Inject Drugs in Tijuana and San Diego: Results From a Binational Cohort Study.

Background: Illicitly manufactured fentanyl (IMF) increases overdose mortality, but its role in infectious disease transmission is unknown. We examined whether IMF use predicts hepatitis C virus (HCV) and human immunodeficiency virus (HIV) incidence among a cohort of people who inject drugs (PWID) in San Diego, California and Tijuana, Mexico.

Methods: PWID were recruited during 2020-2022, undergoing semi-annual interviewer-administered surveys and HIV and HCV serological rapid tests through 2024.

Safe Injection Self-Efficacy is Associated with HCV and HIV Seropositivity Among People Who Inject Drugs in the San Diego-Tijuana Border Region.

Safe injection self-efficacy (SISE) is negatively associated with injection risk behaviors among people who inject drugs (PWID) but has not been examined in differing risk environments. We compared responses to a validated SISE scale between PWID in San Diego, California and Tijuana, Mexico, and examine correlates of SISE among PWID in Tijuana. PWID were recruited via street outreach for a longitudinal cohort study from October 2020-September 2021.

Water, sanitation and hygiene insecurity predict abscess incidence among people who inject drugs in a binational US-Mexico metropolitan area: A longitudinal cohort study.

Introduction: People who inject drugs (PWID) are at high risk of developing injection-related infections, including abscesses. Access to water, sanitation, and hygiene (WASH) are key human rights and services; yet these services have been underexplored as predictors of abscesses among PWID.

Methods: Longitudinal analysis was employed among a cohort of PWID to determine if WASH insecurity (lack of access) was associated with abscess incidence in the Tijuana, Mexico and San Diego, United States metropolitan area during 24-months of follow-up survey data from 2020 to 2023.

Safe Injection Self-Efficacy is associated with HCV and HIV seropositivity among people who inject drugs in the San Diego-Tijuana border region.

Background: Safe injection self-efficacy (SISE) is negatively associated with injection risk behaviors among people who inject drugs (PWID) but has not been examined in differing risk environments. We compared responses to a validated SISE scale between PWID in San Diego, California and Tijuana, Mexico, and examine correlates of SISE among PWID in Tijuana.

Methods: PWID were recruited via street outreach for a longitudinal cohort study from October 2020 - September 2021.

A brief instrument measuring the water, sanitation and hygiene domain of menstrual health among women who inject drugs.

Background: Domains of adequate menstrual health (MH) include access to water, sanitation, and hygiene (WASH). People who menstruate with social disadvantages-such as homelessness or drug injection practices-often face barriers to WASH access. However, validated instruments to measure MH are limited among marginalized populations, and available instruments involve lengthy surveys.

HIV-1 transmission dynamics among people who inject drugs on the US/Mexico border during the COVID-19 pandemic: a prosepective cohort study.

Background: We examined HIV prevalence and transmission dynamics among people who inject drugs in the U.S./Mexico border region during the COVID-19 pandemic.

Changes in injecting versus smoking heroin, fentanyl, and methamphetamine among people who inject drugs in San Diego, California, 2020-2023.

Background: Amidst an increasingly toxic drug supply in North America, people who inject drugs may be transitioning to smoking them. We aimed to assess changes in injecting and smoking opioids and methamphetamine among a cohort of people who inject drugs from San Diego, California.

Methods: Over five six-month periods spanning October 2020-April 2023, we assessed prevalence of injecting and smoking opioids or methamphetamine and whether participants used these drugs more frequently by smoking than injecting.

Water, sanitation, and hygiene access among people who inject drugs in Tijuana and San Diego in 2020-2021: a cross-sectional study.

Background: Water, sanitation, and hygiene (WASH) access is critical to public health and human dignity. People who inject drugs (PWID) experience stigma and structural violence that may limit WASH access. Few studies have assessed WASH access, insecurity, and inequities among PWID.

Changes in injecting versus smoking heroin, fentanyl, and methamphetamine among people who inject drugs in San Diego, California, 2020 to 2023.

Background: Amidst a rapidly evolving drug supply in North America, people who inject drugs may be transitioning to smoking them. We aimed to assess changes in injecting and smoking heroin, fentanyl and methamphetamine among a cohort of people who injected drugs at baseline from San Diego, California.

Methods: Over five six-month periods spanning October 2020-April 2023, we assessed prevalence of injecting and smoking opioids or methamphetamine and whether participants used these drugs more frequently by smoking than injecting.

Health, harm reduction, and social service providers' perspectives on the appropriateness and feasibility of peer distribution of HIV self-test kits among people who use drugs.

Background: People who use drugs (PWUD) experience elevated HIV risk and numerous barriers to facility-based HIV testing. HIV self-testing (HIVST) could circumvent many of those barriers and is acceptable among PWUD, yet HIVST implementation for PWUD is limited. Service providers' perspectives on specific HIVST delivery strategies could help increase availability for PWUD.

Willingness to use and distribute HIV self-testing kits among people who inject drugs in the San Diego-Tijuana border region.

Background: HIV self-testing (HIVST) could increase HIV testing access among people who inject drugs (PWID), and secondary distribution (i.e., peer-delivery) of HIVST kits in PWID social networks could further expand coverage.

WaSH insecurity and anxiety among people who inject drugs in the Tijuana-San Diego border region.

Background: Water, sanitation, and hygiene (WaSH) insecurity increases the risk of water-related diseases. However, limited research has been conducted on psychosocial distress as it relates to WaSH insecurity, especially among people who inject drugs (PWID). We examined the relationship between WaSH insecurity and related anxiety among PWID living in different housing conditions along the US-Mexico border region.

Genomic surveillance reveals dynamic shifts in the connectivity of COVID-19 epidemics.

The maturation of genomic surveillance in the past decade has enabled tracking of the emergence and spread of epidemics at an unprecedented level. During the COVID-19 pandemic, for example, genomic data revealed that local epidemics varied considerably in the frequency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineage importation and persistence, likely due to a combination of COVID-19 restrictions and changing connectivity. Here, we show that local COVID-19 epidemics are driven by regional transmission, including across international boundaries, but can become increasingly connected to distant locations following the relaxation of public health interventions.

A Brief Peer-Led Intervention to Increase COVID-19 Vaccine Uptake Among People Who Inject Drugs in San Diego County: Results From a Pilot Randomized Controlled Trial.

Background: We evaluated the impact of a brief peer-led intervention on COVID-19 vaccination among people who inject drugs (PWID) presenting at syringe services program (SSP) locations in San Diego County, California.

Methods: Between March and July 2022, PWID aged ≥18 years without recent voluntary COVID-19 testing who were not up to date on COVID-19 vaccinations received a single-session motivational interviewing intervention (LinkUP) or an attention-matched didactic control condition from trained peer counselors at SSP sites randomized by week. Following either 30-minute session, counselors offered referrals to local vaccination services.

"": Experiences with rising overdose incidence caused by drug supply changes during the COVID-19 pandemic in the San Diego-Tijuana border metroplex.

Background: People who use drugs (PWUD) in the San Diego, USA and Tijuana, Mexico metroplex face high overdose risk related to historic methamphetamine use and relatively recent fentanyl introduction into local drug supplies. The personal overdose experiences of PWUD in this region are understudied, however, and may have been influenced by the COVID pandemic.

Methods: From September-November 2021, we conducted 28 qualitative interviews among PWUD ≥18 years old sampled from an ongoing cohort study in the San Diego-Tijuana metroplex.

Preliminary Efficacy of a Theory-Informed Intervention to Increase COVID-19 Testing Uptake Among People Who Inject Drugs in San Diego County: Findings From a Pilot Randomized Controlled Trial.

Background: People who inject drugs (PWID) have low rates of COVID-19 testing yet are vulnerable to severe disease. In partnership with a mobile syringe service program (SSP) in San Diego County, CA, we developed the evidence-, community-, and Social Cognitive Theory-informed "LinkUP" intervention (tailored education, motivational interviewing, problem-solving, and planning) to increase COVID-19 testing uptake among PWID.

Purpose: To assess preliminary efficacy of LinkUP in increasing PWID COVID-19 testing in a pilot randomized controlled trial (RCT).

The moderating role of resilience in the relationship between experiences of COVID-19 response-related discrimination and disinformation among people who inject drugs.

Background: Due to the persistence of COVID-19, it remains important to measure and examine potential barriers to COVID-19 prevention and treatment to avert additional loss of life, particularly among stigmatized populations, such as people who inject drugs (PWID), who are at high risk for contracting and spreading SARS-CoV-2. We assessed the psychometrics of a novel COVID-19 response-related discrimination scale among PWID, and characterized associations between COVID-19 response-related discrimination, resilience to adversity, and endorsement of COVID-19 disinformation.

Methods: We assessed internal reliability, structural validity and construct validity of a 4-item COVID-19 response-related discrimination scale among PWID living in San Diego County, completing interviewer-administered surveys between October 2020 and September 2021.

Cocirculation and replacement of SARS-CoV-2 variants in crowded settings and marginalized populations along the US-Mexico border.

Objective: To interrogate the circulating SARS-CoV-2 lin-eages and recombinant variants in persons living in migrant shelters and persons who inject drugs (PWID).

Materials And Methods: We combined data from two studies with marginalized populations (migrants in shelters and persons who inject drugs) in Tijuana, Mexico. SARS-CoV-2 variants were identified on nasal swabs specimens and compared to publicly available genomes sampled in Mexico and California.

Correlates of recent overdose among people who inject drugs in the San Diego/Tijuana border region.

Background: Along the Mexico-US border, illicitly manufactured fentanyls (fentanyl) have been detected in other illicit drugs, including street opioid formulations known as 'china white.' We studied correlates of recent overdose among people who inject drugs (PWID), focusing on the risk of knowlingly or unknowingly using fentanyl in china white.

Methods: From October 2020 - September, 2021 we surveyed participants in San Diego, California and Tijuana, Mexico and employed Poisson regression to identify correlates of recent overdose.

COVID-19 vaccine uptake among people who inject drugs in Tijuana Mexico.

Background: SARS-CoV-2 prevalence is elevated among people who inject drugs (PWID). In Tijuana, Mexico, COVID-19 vaccines became available to the general population in June 2021, but uptake among PWID was <10%. We studied COVID-19 vaccine uptake among PWID in Tijuana following implementation of a pop-up vaccination clinic.

COVID-19 vaccination acceptability and experiences among people who inject drugs in San Diego County.

Background: People who inject drugs (PWID) face increased risk of SARS-CoV-2 acquisition and severe disease, yet COVID-19 vaccine uptake has been suboptimal. To inform vaccination interventions tailored for the needs of this population, we explored COVID-19 vaccination acceptability and experiences among PWID in San Diego County, USA.

Methods: From September-November 2021, we conducted qualitative interviews with PWID aged ≥18 years who were participating in a prospective study of infectious disease risks in San Diego.