Phage therapy: From biological mechanisms to future directions.

Increasing antimicrobial resistance rates have revitalized bacteriophage (phage) research, the natural predators of bacteria discovered over 100 years ago. In order to use phages therapeutically, they should (1) preferably be lytic, (2) kill the bacterial host efficiently, and (3) be fully characterized to exclude side effects. Developing therapeutic phages takes a coordinated effort of multiple stakeholders. Herein, we review the state of the art in phage therapy, covering biological mechanisms, clinical applications, remaining challenges, and future directions involving naturally occurring and genetically modified or synthetic phages.

Expanding antibiotic, vaccine, and diagnostics development and access to tackle antimicrobial resistance.

The increasing number of bacterial infections globally that do not respond to any available antibiotics indicates a need to invest in-and ensure access to-new antibiotics, vaccines, and diagnostics. The traditional model of drug development, which depends on substantial revenues to motivate investment, is no longer economically viable without push and pull incentives. Moreover, drugs developed through these mechanisms are unlikely to be affordable for all patients in need, particularly in low-income and middle-income countries. New, publicly funded models based on public-private partnerships could support investment in antibiotics and novel alternatives, and lower patients' out-of-pocket costs, making drugs more accessible. Cost reductions can be achieved with public goods, such as clinical trial networks and platform-based quality assurance, manufacturing, and product development support. Preserving antibiotic effectiveness relies on accurate and timely diagnosis; however scaling up diagnostics faces technological, economic, and behavioural challenges. New technologies appeared during the COVID-19 pandemic, but there is a need for a deeper understanding of market, physician, and consumer behaviour to improve the use of diagnostics in patient management. Ensuring sustainable access to antibiotics also requires infection prevention. Vaccines offer the potential to prevent infections from drug-resistant pathogens, but funding for vaccine development has been scarce in this context. The High-Level Meeting of the UN General Assembly in 2024 offers an opportunity to rethink how research and development can be reoriented to serve disease management, prevention, patient access, and antibiotic stewardship.

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. Cox regression was conducted to examine predictors of seroconversion considering self-reported IMF use as a 6-month lagged, time-dependent covariate. RESULTS: Of 398 PWID at baseline, 67% resided in San Diego, 70% were male, median age was 43 years, 42% reported receptive needle sharing, and 25% reported using IMF. HCV incidence was 14.26 per 100 person-years (95% confidence interval [CI]: 11.49-17.02), and HIV incidence was 1.29 (95% CI: .49-2.10). IMF was associated with HCV seroconversion, with a univariable hazard ratio (HR) of 1.64 (95% CI: 1.09-2.40), and multivariable HR of 1.57 (95% CI: 1.03-2.40). The direction of the relationship with HIV was similar, albeit not significant (HR 2.39; 95% CI: .66-8.64). CONCLUSIONS: We document a novel association between IMF and HCV seroconversion among PWID in Tijuana-San Diego. Few HIV seroconversions (n = 10) precluded our ability to assess if a similar relationship held for HIV. IMF's short half-life may destabilize PWID-increasing the need for repeat dosing and sharing smoking materials and syringes. New preventive care approaches may reduce HCV transmission in the fentanyl era.

Managing HIV During the COVID-19 Pandemic: A Study of Help-Seeking Behaviors on a Social Media Forum.

Although numerous editorials claim the COVID-19 pandemic has disproportionately impacted vulnerable populations, particularly those affected by HIV, these claims have received limited empirical evaluation. We analyzed posts to Reddit's r/HIVAIDS from January 3, 2012 through April 30, 2022 to (a) assess changes in the volume of posts during the pandemic and (b) determine the needs of HIV affected communities. There were cumulatively 100% (95%CI: 75-126) more posts than expected since the US declared a pandemic emergency. The most prevalent themes in these posts were for obtaining an HIV + diagnosis (representing 34% (95%CI:29-40) of all posts), seeking HIV treatment (20%; 95%CI:16-25), finding psychosocial support (16%; 95%CI:12-20), and tracking disease progression (8%; 95%CI:5-11). Discussions about PrEP and PEP were the least common, representing less than 6% of all posts each. Social media has increasingly become an important health resource for vulnerable populations seeking information, advice, and support. Public health organizations should recognize how the lay public uses social media and collaborate with social media companies to ensure that the needs of help-seekers on these platforms are met.

Long-acting Injectable PrEP Interest and General PrEP Awareness among People who Inject Drugs in the San Diego-Tijuana Border Metroplex.

Long-acting injectable HIV pre-exposure prophylaxis (LAI-PrEP) could help overcome multilevel challenges to HIV prevention for people who inject drugs (PWID), including those in the binational San Diego-Tijuana metroplex. Yet, general PrEP awareness and interest in LAI-PrEP remain underexplored among PWID. From 2020 to 2021, 562 HIV-negative PWID in San Diego and Tijuana completed surveys assessing general PrEP awareness and interest in oral and LAI-PrEP. Modified Poisson regression examined factors associated with general PrEP awareness. Multinomial logistic regression assessed factors associated with interest in both oral and LAI-PrEP, oral PrEP only, LAI-PrEP only, or neither. General PrEP awareness was low (18%) and associated with experiencing unsheltered homelessness (adjusted prevalence ratio [APR] = 1.50, 95% confidence interval [CI]: 0.96-2.33), past 6-month fentanyl injection (APR = 1.53, 95% CI: 1.04-2.25), and transactional sex (APR = 1.71, 95% CI: 1.06-2.76). Interest in oral PrEP only was most common (44%), followed by LAI-PrEP only (25%) and neither (16%). Compared to the odds of being interested in LAI-PrEP only, the odds of being interested in oral PrEP only were lower among those who were stopped by police (AOR = 0.38, 95% CI: 0.22-0.65), reported past 6-month fentanyl injection (AOR = 0.33, 95% CI: 0.20-0.56), polydrug use (AOR = 0.48, 95% CI: 0.27-0.86), injecting multiple times daily (AOR = 0.26, 95% CI: 0.14-0.46), receptive syringe use (AOR = 0.30, 95% CI: 0.19-0.49), and higher perceived HIV risk (AOR = 0.24, 95% CI: 0.15-0.39). Interest in LAI-PrEP was more common among PWID reporting social and structural factors that could interfere with oral PrEP adherence, suggesting LAI-PrEP implementation could increase PrEP coverage among those most vulnerable to HIV.

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. We compared SISE scale items by city. Due to low variability in SISE scores among San Diego residents, we restricted analysis of factors associated with SISE to Tijuana residents and identified correlates of SISE score levels (low, medium, high) using ordinal logistic regression. Of 474 participants, most were male (74%), Latinx (78%) and Tijuana residents (73%). Mean age was 44. Mean SISE scores among San Diego residents were high (3.46 of 4 maximum) relative to Tijuana residents (mean: 1.93). Among Tijuana residents, White race and having previously resided in San Diego were associated with higher SISE scores. HCV and HIV seropositivity, homelessness, fentanyl use, polysubstance co-injection, and greater injection frequency were associated with lower SISE scores. We found profound inequalities between Tijuana and San Diego SISE, likely attributable to differential risk environments. Associations with fentanyl and polysubstance co-injection, injection frequency, and both HIV and HCV seropositivity suggest that SISE contribute to blood-borne infection transmission risks in Tijuana. SISE reflects an actionable intervention target to reduce injection risk behaviors, but structural interventions are required to change the risk environment.

RESUMEN: La autoeficacia de inyección segura (SISE, por sus siglas en inglés) se asocia negativamente con conductas de riesgo de inyección entre las personas que se inyectan drogas (PWID, por sus siglas en inglés), pero no se ha examinado en diferentes entornos de riesgo. Comparamos las respuestas a una escala validada de SISE entre PWID en San Diego, California, y Tijuana, México, y examinamos los correlatos de SISE entre PWID en Tijuana. Participantes fueron reclutados por medio de alcance callejero para un estudio de cohorte longitudinal entre octubre 2020 ­septiembre de 2021. Comparamos los ítems de la escala SISE por ciudad. Debido a la baja variabilidad en los puntajes SISE entre los residentes de San Diego, restringimos el análisis de factores asociados con SISE a los residentes de Tijuana e identificamos factores correlacionados con niveles de SISE (bajo, medio, alto) mediante regresión logística ordinal. De 474 participantes, la mayoría eran hombres (74%), latinx (78%) y residentes de Tijuana (73%). La edad promedio fue de 44 años. Los puntajes medios de SISE entre los residentes de San Diego fueron altos (3.46 de un máximo de 4) en comparación con los residentes de Tijuana (media: 1.93). Entre los residentes de Tijuana, la raza blanca y haber residido previamente en San Diego se asociaron con puntajes más altos de SISE. La seropositividad para HCV y VIH, la falta de vivienda, el uso de fentanilo, la co-inyección de múltiples sustancias y una mayor frecuencia de inyecciónes se asociaron con puntajes más bajos de SISE. Encontramos profundas desigualdades entre SISE en Tijuana y San Diego, probablemente atribuibles a diferentes entornos de riesgo. Las asociaciones con fentanilo y la co-inyección de múltiples sustancias, la frecuencia de inyección y la seropositividad tanto para VIH como para HCV sugieren que SISE contribuye a los riesgos de transmisión de infecciones transmitidas por la sangre en Tijuana. SISE refleja un objetivo de intervención accionable para reducir las conductas de riesgo de inyección, pero se requieren intervenciones estructurales para cambiar el entorno de riesgo.

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. We describe WASH access, social and geographic inequalities, and factors associated with WASH insecurity among PWID in the Tijuana-San Diego metropolitan area. METHODS: In this cross-sectional binational study, we interviewed PWID (age 18+) in 2020-2021 about WASH access and insecurity. City of residence (Tijuana/San Diego) and housing status were considered as independent variables to describe key WASH access outcomes and to assess as factors associated with WASH insecurity outcomes. Measures of association between outcomes and independent variables were assessed using log modified-Poisson regression models adjusting for covariates. RESULTS: Of 586 PWID (202 Tijuana; 384 San Diego), 89% reported basic access to drinking water, 38% had basic hand hygiene, 28% basic sanitation, and 46% access to bathing, and 38% reported recent open defecation. Participants residing in Tijuana reported significantly higher insecurity in accessing basic drinking water (aRR: 1.68, 95%CI: 1.02-2.76), basic hygiene (aRR: 1.45, 95%CI: 1.28-1.64), and bathing (aRR: 1.21, 95%CI: 1.06-1.39) than those living in San Diego. Participants experiencing unsheltered homelessness experienced significantly higher insecurity in accessing basic drinking water (aRR: 2.03, 95%CI: 1.07-3.86), basic sanitation (aRR: 1.68, 95%CI: 1.48, 1.92), bathing (aRR: 1.84, 95%CI: 1.52-2.22), and improved water sources for cleaning wounds (aRR: 3.12, 95%CI: 1.55-6.29) and for preparing drugs (aRR: 2.58, 95%CI: 1.36-4.89) than participants living in permanent housing. CONCLUSION: WASH access among PWID in the Tijuana-San Diego metropolitan area was low by international standards and lower than the national averages in both countries. Homelessness was significantly associated with WASH insecurity in this population. Concentrated efforts are needed to guarantee continuously available WASH services for PWID-especially those who are unsheltered.

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. METHODS: From 2020-2021, a cross-sectional study was conducted among 585 people who injected drugs within the last month in Tijuana (N = 202), San Diego (N = 182), and in both Tijuana and San Diego (N = 201). Participants underwent interviewer-administered surveys related to WaSH access, substance use, and generalized anxiety disorder (GAD-7). Quasi-Poisson regressions were used to assess associations between WaSH insecurity and anxiety in the prior 6-months. RESULTS: Participants were 75% male, 42% were unhoused and 91% experienced WaSH insecurity in the prior 6-months. After adjusting for housing status, gender, and age, lack of access to basic drinking water (Adj RR: 1.28; 95% CI: 1.02-1.58), sanitation (Adj RR:1.28; 95% CI: 1.07-1.55), and a daily bath/shower (Adj RR: 1.38; 95% CI: 1.15-1.66) were associated with mild-severe anxiety. The number of WaSH insecurities was independently associated with a 20% increased risk of experiencing anxiety per every additional insecurity experienced (Adj RR: 1.20; CI: 1.12-1.27). We also found a significant interaction between gender and housing status (p = 0.003), indicating that among people experiencing sheltered/unsheltered homelessness, women had a higher risk of mild-severe anxiety compared to men (Adj RR: 1.55; 95% CI: 1.27-1.89). At the same time, among women, those who are unhoused have 37% increased risk of anxiety than those who live in stable housing conditions (Adj RR: 1.37; 95% CI: 1.01-1.89). CONCLUSION: The lack of specific WaSH services, particularly lack of drinking water, toilets, and daily showers were associated with higher levels of anxiety among PWID in the Tijuana-San Diego border region. Women experiencing homelessness were especially vulnerable. WaSH interventions that provide safe, 24-h access may help to reduce anxiety and health risks associated with WaSH insecurity.

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. We assessed willingness to use and distribute HIVST kits among PWID in the San Diego-Tijuana border region. METHODS: From 2020 to 2021, HIV-negative PWID in San Diego, USA, and Tijuana, Mexico, completed surveys and provided data on individual (N = 539) and social network (N = 366) characteristics. We used modified Poisson regression to examine the effects of individual and social network characteristics on willingness to use and distribute HIVST kits. RESULTS: Most participants were willing to use (81%) and distribute (81%) HIVST kits. At the individual level, prior HIV testing was positively associated with willingness to use (adjusted prevalence ratio [aPR] = 1.24, 95% confidence interval [CI] 1.10-1.40) and distribute (aPR = 1.27, 95% CI 1.12-1.43) HIVST kits, while perceiving oneself to be at higher HIV risk than others was negatively associated with willingness to use HIVST kits (aPR = 0.83, 95% CI 0.74-0.93). At the network level, willingness to distribute HIVST kits was positively associated with network size (aPR = 1.04 per member, 95% CI 1.01-1.08) and greater proportions of one's network encouraging them to use drugs (aPR = 1.29, 95% CI 1.16-1.44) and having a history of homelessness (aPR = 1.51, 95% CI 1.31-1.74) or detention/arrest (aPR = 1.57, 95% CI 1.36-1.82), and negatively associated with a greater proportion of one's network including "very close" persons (aPR = 0.80, 95% CI 0.69-0.94). CONCLUSIONS: We found high potential for HIVST kits and their secondary distribution to increase HIV testing among PWID who face the greatest barriers to facility-based testing.

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. METHODS: From April-November 2021, we interviewed 16 health, harm reduction, and social service providers working with PWUD in San Diego, CA. Interviews and rapid thematic analysis explored perspectives on HIVST's utility and appropriateness, as well as the feasibility of and anticipated challenges with specific HIVST delivery strategies, including peer or secondary distribution. RESULTS: Participants viewed HIV as a significant threat to PWUD health and confirmed the presence of numerous barriers to local facility-based HIV testing. Participants viewed HIVST as a promising and potentially empowering solution. Based on community familiarity with secondary distribution of harm reduction supplies (i.e., naloxone) and information, participants viewed secondary distribution of HIVST kits as an appropriate and feasible strategy for increasing the reach of HIVST, but also described potential barriers (e.g., engaging socially disconnected individuals, ensuring linkages to services following HIVST) and provided suggestions for alternative HIVST kit delivery models (e.g., harm reduction vending machines). CONCLUSIONS: Service providers viewed secondary distribution of HIVST kits among PWUD as promising, appropriate, and feasible, yet specialized efforts may be needed to reach the most marginalized individuals and ensure consistent provision of educational information and referral supports that maximize the impact of this approach.

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). METHODS: We referred participants (PWID, ≥18 years old, San Diego County residents who had not recently undergone voluntary COVID-19 testing) to mobile SSP sites that had been randomized (by week) to offer the active LinkUP intervention or didactic attention-control conditions delivered by trained peer counselors. Following either condition, counselors offered on-site rapid COVID-19 antigen testing. Analyses estimated preliminary intervention efficacy and explored potential moderation. RESULTS: Among 150 participants, median age was 40.5 years, 33.3% identified as Hispanic/Latinx, 64.7% were male, 73.3% were experiencing homelessness, and 44.7% had prior mandatory COVID-19 testing. The LinkUP intervention was significantly associated with higher COVID-19 testing uptake (p < .0001). Homelessness moderated intervention effects; LinkUP increased COVID-19 testing uptake more among participants experiencing homelessness (adjusted risk ratio [aRR]: 1.80; 95% CI: 1.56-2.09; p < .0001) than those not experiencing homelessness (aRR: 1.20; 95% CI: 1.01-1.43; p = .04). CONCLUSIONS: Findings from this pilot RCT support the preliminary efficacy of the "LinkUP" intervention to increase COVID-19 testing among PWID and underscore the importance of academic-community partnerships and prevention service delivery through SSPs and other community-based organizations serving vulnerable populations.

People who inject drugs (PWID) are vulnerable to severe COVID-19 disease yet have low rates of COVID-19 testing. We partnered with a syringe service program (SSP) in San Diego County, CA, to develop "LinkUP," an evidence- and community-informed intervention. Specifically, LinkUP used tailored education, motivational interviewing, and problem-solving and planning strategies to increase COVID-19 testing uptake among PWID. This study was a pilot randomized controlled trial (RCT) designed to assess the preliminary efficacy of LinkUP in increasing PWID COVID-19 testing. We referred participants (PWID, ≥18 years old, San Diego residents without recent voluntary COVID-19 testing) to mobile SSP sites that had been randomized (by week). Trained peer counselors then offered LinkUP or an educational control condition lasting the same length (~30 minutes). After either condition, counselors offered on-site rapid COVID-19 antigen testing. Among 150 participants, our analyses found that the LinkUP intervention was associated with higher COVID-19 testing uptake, especially for participants experiencing homelessness. In summary, our findings from this pilot RCT support the preliminary efficacy of the "LinkUP" intervention in increasing COVID-19 testing among PWID. This study also underscores the importance of academic-community partnerships and prevention service delivery through SSPs and other community-based organizations serving vulnerable populations.

Network-level HIV risk norms are associated with individual-level HIV risk and harm reduction behaviors among people who inject drugs: a latent profile analysis.

The COVID-19 related U.S.-Mexico border-crossing restrictions disrupted social networks and HIV harm reduction services among people who inject drugs (PWID) in San Diego and Tijuana. We assessed associations of descriptive network norms on PWID's HIV vulnerability during this period. Between 10/2020 and 10/2021, 399 PWID completed a behavioral and egocentric questionnaire. We used Latent Profile Analysis to categorize PWID into network norm risk profiles based on proportions of their network (n = 924 drug use alters) who injected drugs and engaged in cross-border drug use (CBDU), among other vulnerabilities. We used logistic and linear regressions to assess network profile associations with individual-level index of HIV vulnerability and harm reduction behaviors. Fit indices specified a 4-latent profile solution of descriptive network risk norms: lower (n = 178), moderate with (n = 34) and without (n = 94) CBDU and obtainment, and higher (n = 93). Participants in higher risk profiles reported more HIV vulnerability behaviors and fewer harm reduction behaviors. PWID's gradient of HIV risk was associated with network norms, warranting intervention on high-vulnerability networks when services are limited.

Hepatitis C Virus in people with experience of injection drug use following their displacement to Southern Ukraine before 2020.

BACKGROUND: Due to practical challenges associated with genetic sequencing in low-resource environments, the burden of hepatitis C virus (HCV) in forcibly displaced people is understudied. We examined the use of field applicable HCV sequencing methods and phylogenetic analysis to determine HCV transmission dynamics in internally displaced people who inject drugs (IDPWID) in Ukraine. METHODS: In this cross-sectional study, we used modified respondent-driven sampling to recruit IDPWID who were displaced to Odesa, Ukraine, before 2020. We generated partial and near full length genome (NFLG) HCV sequences using Oxford Nanopore Technology (ONT) MinION in a simulated field environment. Maximum likelihood and Bayesian methods were used to establish phylodynamic relationships. RESULTS: Between June and September 2020, we collected epidemiological data and whole blood samples from 164 IDPWID (PNAS Nexus.2023;2(3):pgad008). Rapid testing (Wondfo® One Step HCV; Wondfo® One Step HIV1/2) identified an anti-HCV seroprevalence of 67.7%, and 31.1% of participants tested positive for both anti-HCV and HIV. We generated 57 partial or NFLG HCV sequences and identified eight transmission clusters, of which at least two originated within a year and a half post-displacement. CONCLUSIONS: Locally generated genomic data and phylogenetic analysis in rapidly changing low-resource environments, such as those faced by forcibly displaced people, can help inform effective public health strategies. For example, evidence of HCV transmission clusters originating soon after displacement highlights the importance of implementing urgent preventive interventions in ongoing situations of forced displacement.

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. RESULTS: All but 2 of the 10 lineages identified were predomi-nantly detected in North and Central America. Discrepan-cies between migrants and PWID can be explained by the temporal emergence and short time span of most of these lineages in the region. CONCLUSION: The results illustrate the temporo-spatial structure for SARS-CoV-2 lineage dispersal and the potential co-circulation of multiple lineages in high-risk populations with close social contacts. These conditions create the potential for recombination to take place in the California-Baja California border.

Correlates of impulsivity among female sex workers in Mexico.

Impulsivity is a trait characteristic that is associated with sexual risk behavior. We examined correlates of impulsivity among 602 female sex workers (FSWs) enrolled in a sexual risk reduction intervention in Mexico (2016-2020). Impulsivity was positively associated with condomless sex with clients. Higher levels of impulsivity were associated with greater use of alcohol and heavy drugs, use of illicit drugs with clients, sexual/physical abuse history, and clinical depression. Global public health policy that supports free substance abuse treatment in combination with psychotherapeutic treatments (e.g. regulation management skills) and behavioral-focused therapy may help to reduce HIV/STI incidence in this vulnerable population.

Correlates of Coronavirus Disease 2019 (COVID-19) Vaccine Hesitancy Among People Who Inject Drugs in the San Diego-Tijuana Border Region.

BACKGROUND: People who inject drugs (PWID) are vulnerable to acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We examined correlates of coronavirus disease 2019 (COVID-19) vaccine hesitancy among PWID in the US-Mexico border region, of whom only 7.6% had received ≥ 1 COVID-19 vaccine dose by September 2021. METHODS: Between October 2020 and September 2021, participants aged ≥ 18 years from San Diego, California, USA, and Tijuana, Baja California, Mexico, who injected drugs within the last month completed surveys and SARS-CoV-2, human immunodeficiency virus (HIV), and hepatitis C virus (HCV) serologic testing. Logistic regressions with robust standard error estimation via generalized estimating equations identified factors associated with being unsure or unwilling to receive COVID-19 vaccines. RESULTS: Of 393 participants, 266 (67.7%) were willing to receive COVID-19 vaccines and 127 (32.3%) were hesitant (23.4% unwilling and 8.9% unsure). Older participants, those with greater food insecurity, and those with greater concern about acquiring SARS-CoV-2 were more willing to be vaccinated. Higher numbers of chronic health conditions, having access to a smart phone or computer, and citing social media as one's most important source of COVID-19 information were independently associated with vaccine hesitancy. COVID-19-related disinformation was independently associated with vaccine hesitancy (adjusted odds ratio: 1.51 per additional conspiracy theory endorsed; 95% confidence interval: 1.31-1.74). CONCLUSIONS: Nearly one third of people injecting drugs in the US-Mexico border region were COVID-19 vaccine hesitant, which was significantly associated with exposure to social media, disinformation and co-morbidities and inversely associated with food security and high perceived threat of COVID-19. Interventions that improve accurate knowledge of and trust in COVID-19 vaccines are needed in this vulnerable population.

The opioid crisis and HIV in the USA: deadly synergies.

The opioid epidemic is one of the greatest public health problems that the USA faces. Opioid overdose death rates have increased steadily for more than a decade and doubled in 2013-17, as the highly potent synthetic opioid fentanyl entered the drug supply. Demographics of new HIV diagnoses among people who inject drugs are also changing, with more new HIV diagnoses occurring among White people, young people (aged 13-34 years), and people who reside outside large central metropolitan areas. Racial differences also exist in syringe sharing, which decreased among Black people and Hispanic people but remained unchanged among White people in 2005-15. Recent HIV outbreaks have occurred in rural areas of the USA, as well as among marginalised people in urban areas with robust HIV prevention and treatment services (eg, Seattle, WA). Multiple evidence-based interventions can effectively treat opioid use disorder and prevent HIV acquisition. However, considerable barriers exist precluding delivery of these solutions to many people who inject drugs. If the USA is serious about HIV prevention among this group, stigma must be eliminated, discriminatory policies must change, and comprehensive health care must be accessible to all. Finally, root causes of the opioid epidemic such as hopelessness need to be identified and addressed.

Impact of SHIELD Police Training on Knowledge of Syringe Possession Laws and Related Arrests in Tijuana, Mexico.

Between 2015 and 2018, we provided training for 1806 municipal police officers in Tijuana, Mexico, in an effort to improve their knowledge and behaviors related to HIV and injection drug use. Correct knowledge of syringe possession laws improved from 56% before training to 94% after training and was sustained at 24 months (75%). Knowledge improvement was associated with decreases in arrests for syringe possession over time (adjusted odds ratio [AOR] = 0.87; 95% confidence interval [CI] = 0.85, 0.90). Officers with correct knowledge had significantly lower odds of reporting arrests (AOR = 0.63; 95% CI = 0.44, 0.89). Training was associated with sustained improvements in knowledge and practices that advance public health. (Am J Public Health. 2022;112(6):860-864. https://doi.org/10.2105/AJPH.2021.306702).

An Ethnographic Assessment of COVID-19‒Related Changes to the Risk Environment for People Who Use Drugs in Tijuana, Mexico.

Objectives. To characterize the effects of the onset of the COVID-19 pandemic on the risk environment of people who use drugs (PWUD) in Tijuana, Mexico. Methods. We used intensive participant-observation ethnography among street-based PWUD and key informants, such as frontline physicians and harm reductionists. Results. PWUD described an unprecedented cessation of police violence and extortion during the initial pandemic-related lockdown, though this quickly reversed and police violence worsened. Government-provided housing and medical treatment with methadone were temporarily provided to PWUD in a dedicated clinic, yet only for PWUD with COVID-19 symptoms. Concurrently, non‒COVID-19‒related hospital care became virtually inaccessible, and many PWUD died of untreated, chronic illnesses, such as hepatitis C, and soft-tissue infections. Border closures, decreases in social interaction, and reduced drug and sex tourism resulted in worsening food, income, and housing insecurity for many PWUD. By contrast, potent illicit drugs remained easily accessible in open-air drug markets. Conclusions. The pandemic exacerbated health risks for PWUD but also offered profound glimpses of beneficial structural changes. Efforts are needed in Tijuana and elsewhere to institutionalize positive pandemic-related shifts and ameliorate novel harms for PWUD. (Am J Public Health. 2022;112(S2):S199-S202. https://doi.org/10.2105/AJPH.2022.306796).

A cross-sectional study of factors associated with COVID-19 testing among people who inject drugs: missed opportunities for reaching those most at risk.

BACKGROUND: People who inject drugs (PWID) are vulnerable to SARS-CoV-2 infection. We examined correlates of COVID-19 testing among PWID in the U.S.-Mexico border region and described encounters with services representing potential opportunities (i.e., 'touchpoints') where COVID-19 testing could have been offered. METHODS: Between October, 2020 and September, 2021, participants aged ≥18 years from San Diego, California, USA and Tijuana, Baja California, Mexico who injected drugs within the last month completed surveys and SARS-CoV-2, HIV, and HCV serologic testing. Logistic regression identified factors associated with COVID-19 testing including potential touchpoints, comorbidities and COVID-19 related misinformation and disinformation. RESULTS: Of 583 PWID, 30.5% previously had a COVID-19 test. Of 172 PWID who tested SARS-CoV-2 seropositive (30.1%), 50.3% encountered at least one touchpoint where COVID-19 testing could have been offered within the prior six months. Factors independently associated with at least two fold higher odds of COVID-19 testing were living in San Diego, recent incarceration, receiving substance use treatment, and experiencing ≥1 chronic health condition. Homelessness, having received ≥1 dose of COVID-19 vaccine, and having a HIV or HCV test since the COVID-19 epidemic began were also independently associated with having had a prior COVID-19 test. CONCLUSION: We identified several factors independently associated with COVID-19 testing and multiple touchpoints where COVID-19 testing could be scaled up for PWID, such as SUD treatment programs and syringe service programs. Integrated health services are needed to improve access to rapid, free COVID-19 testing in this vulnerable population.