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

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.

The Detection of Xylazine in Tijuana, Mexico: Triangulating Drug Checking and Clinical Urine Testing Data

Introduction

Xylazine is a veterinary anesthetic increasingly present alongside illicit fentanyl in the US and Canada, presenting novel health risks. Although xylazine remains less common in the Western US, Mexican border cities serve as key trafficking hubs and may have higher prevalence of novel substances, but surveillance has been limited.

Methods

We examined deidentified records from the Prevencasa harm reduction clinic in Tijuana, describing urine and paraphernalia testing from patients reporting using illicit opioids within 24 hr. Xylazine (two types), fentanyl, opiate, methamphetamine, amphetamine, benzodiazepine, and nitazene test strips were used to test urine and paraphernalia samples. Paraphernalia samples were also analyzed with mass spectrometry.

Results

The study consisted of 23 participants that provided both urine and paraphernalia samples. Of the participants studied, 100 %, 91.3 %, and 69.6 % reported using China White/fentanyl, methamphetamine, and tar heroin, respectively. The mean age was 41.7 years, 95.7 % were male, 65.2 % were unhoused, and 30.4 % had skin wounds at the time of sample collection.Xylazine positivity in urine, for the two types used, was 82.6 % and 65.2 %. For paraphernalia testing, the xylazine positivity was 65.2 % and 47.8 %. Confirmatory testing of paraphernalia samples by mass spectrometry indicated a 52.2 % xylazine positivity. This testing also revealed positivity rates for fentanyl (73.9 %), fluorofentanyl (30.4 %), tramadol (30.4 %), and lidocaine (30.4 %).The mass spectrometry results suggest lidocaine triggered n = 3 and n = 0 false positives among the xylazine test strip types. A total of n = 0 and n = 1 false negatives were also observed.

Discussion

Xylazine is present on the U.S.-Mexico border, requiring public health intervention. High lidocaine positivity complicates the clinical detection of xylazine via testing strips. Xylazine was found to be more prevalent in urine than in paraphernalia samples. Confirmatory urine studies are needed to better understand possible complications of using test strips for toxicological testing.

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. We developed and evaluated psychometric properties of a novel 'MH WASH Domain Scale-12' among people who menstruate and who inject drugs in the Tijuana-San Diego region and identified correlates of MH access using this scale.

METHODS

We constructed a MH-scale based on access to twelve WASH-related items: (1) menstrual products, (2) body hygiene (bathing per week), (3) water sources for bathing, (4) improved, (5) non-shared, (6) available, (7) private, (8) nearby, (9) and safe sanitation facilities, (10) availability of soap, (11) water source for handwashing, and (12) handwashing facilities with soap/water. Variables were dichotomized and summed, with scores ranging from 0-12 points and higher scores indicating better MH access. We assessed the scale's reliability and construct and content validity using data from a binational cross-sectional study. The sample included people who inject drugs (PWID) who had ever menstruated in their lifetime and were 18+ during 2020-2021. MH-WASH items were described, and the scale was further used as an outcome variable to identify correlates.

RESULTS

Among 125 (124 cis-female and 1 trans-male) PWID that reported menstruating, our 'MH WASH Domain Scale-12' was reliable (Cronbach's alpha = 0.81, McDonald's Omega total = 0.83) and valid. We identified two sub-domains: Factor-1 included items describing 'WASH availability' and Factor-2 contained items related to 'WASH security'-encompassing physical and biological safety. Scale scores were significantly lower among participants experiencing unsheltered homelessness compared to participants experiencing sheltered homelessness or living in permanent housing.

CONCLUSION

We constructed and validated a novel and reliable scale to measure MH-related WASH access that can be used to assess MH among marginalized populations in English- and Spanish-speaking contexts. Using this scale we identified disparities in MH-WASH access among PWID and who menstruate in the US-Mexico border region.

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.

Methods

People who inject drugs aged ≥18 years from 3 groups were recruited: people who inject drugs who live in San Diego (SD) and engaged in cross-border drug use in Tijuana, Mexico (SD CBDUs), and people who inject drugs in SD and Tijuana (TJ) who did not engage in cross-border drug use (NCBDUs). We computed HIV prevalence at baseline and bivariate incidence-density rates (IR) at 18-month follow-up. Bayesian phylogenetic analysis was used to identify local transmission clusters, estimate their age, and effective reproductive number (Re) over time within the clusters.

Findings

At baseline (n = 612), 26% of participants were female, 9% engaged in sex work, and HIV prevalence was 8% (4% SD CBDU, 4% SD NCBDU, 16% TJ NCBDU). Nine HIV seroconversions occurred over 18 months, IR: 1.357 per 100 person-years (95% CI: 0.470, 2.243); 7 in TJ NCBDU and 2 in SD CBDU. Out of 16 identified phylogenetic clusters, 9 (56%) had sequences from both the U.S. and Mexico (mixed-country). The age of three youngest mixed-country dyads (2018-2021) overlapped with the COVID-related US-Mexico border closure in 2020. One large mixed-country cluster (N = 15) continued to grow during the border closure (Re = 4.8, 95% Highest Posterior Density (HPD) 1.5-9.1) with 47% engaging in sex work.

Interpretation

Amidst the COVID-19 pandemic and the border closure, cross-border HIV clusters grew. Efforts to end the HIV epidemic in the U.S. should take into account cross-border HIV-1 transmission from Tijuana. Mobile harm reduction services and coordination with municipal HIV programs to initiate anti-retroviral therapy and pre-exposure prophylaxisis are needed to reduce transmission.

Funding

This research was supported by the James B. Pendleton Charitable Trust and the San Diego Center for AIDS Research.

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.

Estimating the impact of a police education program on hepatitis C virus transmission and disease burden among people who inject drugs in Tijuana, Mexico: A dynamic modeling analysis

BACKGROUND AND AIMS

Criminalization of drug use and punitive policing are key structural drivers of hepatitis C virus (HCV) risk among people who inject drugs (PWID). A police education program (Proyecto Escudo) delivering training on occupational safety together with drug law content was implemented between 2015 and 2016 in Tijuana, Mexico, to underpin drug law reform implementation. We used data from a longitudinal cohort of PWID in Tijuana to inform epidemic modeling and assess the long-term impact of Escudo on HCV transmission and burden among PWID in Tijuana.

METHODS

We developed a dynamic, compartmental model of HCV transmission and incarceration among PWID and tracked liver disease progression among current and former PWID. The model was calibrated to data from Tijuana, Mexico, with 90% HCV seroprevalence. We used segmented regression analysis to estimate impact of Escudo on recent incarceration among an observational cohort of PWID. By simulating the observed incarceration trends, we estimated the potential impact of the implemented (2-year reduction in incarceration) and an extended (10-year reduction in incarceration) police education program over a 50-year follow-up (2016-2066) on HCV outcomes (incidence, cirrhosis, HCV-related deaths and disability adjusted life-years averted) compared with no intervention.

RESULTS

Over the 2-year follow-up, Proyecto Escudo reduced HCV incidence among PWID from 21.5 per 100 person years (/100py) (95% uncertainty interval [UI] = 15.3-29.7/100py) in 2016 to 21.1/100py (UI = 15.0-29.1/100py) in 2018. If continued for 10 years, Escudo could reduce HCV incidence to 20.0/100py (14.0-27.8/100py) by 2026 and avert 186 (32-389) new infections, 76 (UI = 12-160) cases of cirrhosis and 32 (5-73) deaths per 10 000 PWID compared with no intervention over a 50-year time horizon.

CONCLUSIONS

In Tijuana, Mexico, implementation of a police education program delivering training on occupational safety and drug law content appears to have reduced hepatitis C virus incidence among people who inject drugs.

Fentanyl, heroin, and methamphetamine-based counterfeit pills sold at tourist-oriented pharmacies in Mexico: An ethnographic and drug checking study

BACKGROUND

Fentanyl- and methamphetamine-based counterfeit prescription drugs have driven escalating overdose death rates in the US, however their presence in Mexico has not been assessed. Our ethnographic team has conducted longitudinal research focused on illicit drug markets in Northern Mexico since 2018. In 2021-2022, study participants described the arrival of new, unusually potent tablets sold as ostensibly controlled substances, without a prescription, directly from pharmacies that cater to US tourists.

AIMS

To characterize the availability of counterfeit and authentic controlled substances at pharmacies in Northern Mexico available to English-speaking tourists without a prescription.

METHODS

We employed an iterative, exploratory, mixed methods design. Longitudinal ethnographic data was used to characterize tourist-oriented micro-neighborhoods and guide the selection of n=40 pharmacies in n=4 cities in Northern Mexico. In each pharmacy, samples of "oxycodone", "Xanax", and "Adderall" were sought as single pills, during English-language encounters, after which detailed ethnographic accounts were recorded. We employed immunoassay-based testing strips to check each pill for the presence of fentanyls, benzodiazepines, amphetamines, and methamphetamines. We used Fourier-Transform Infrared Spectroscopy to further characterize drug contents.

RESULTS

Of n=40 pharmacies, one or more of the requested controlled substances could be obtained with no prescription (as single pills or in bottles) at 28 (70.0%) and as single pills at 19 (47.5%). Counterfeit pills were obtained at 11 pharmacies (27.5%). Of n=45 samples sold as one-off controlled substances, 18 were counterfeit. 7 of 11 (63.6%) samples sold as "Adderall" contained methamphetamine, 8 of 27 (29.6%) samples sold as "Oxycodone" contained fentanyl, and 3 "Oxycodone" samples contained heroin. Pharmacies providing counterfeit drugs were uniformly located in tourist-serving micro-neighborhoods, and generally featured English-language advertisements for erectile dysfunction medications and "painkillers". Pharmacy employees occasionally expressed concern about overdose risk and provided harm reduction guidance.

DISCUSSION

The availability of fentanyl-, heroin-, and methamphetamine-based counterfeit medications in tourist-oriented independent pharmacies in Northern Mexico represents a public health risk, and occurs in the context of 1) the normalization of medical tourism as a response to rising unaffordability of healthcare in the US, 2) plummeting rates of opioid prescription in the US, affecting both chronic pain patients and the availability of legitimate pharmaceuticals on the unregulated market, 3) the rise of fentanyl-based counterfeit opioids as a key driver of the fourth, and deadliest-to-date, wave of the opioid crisis. It was not possible to distinguish counterfeit medications based on appearance of pills or geography of pharmacies, because identically-appearing authentic and counterfeit versions were often sold in close geographic proximity. Nevertheless, people who consume drugs may be more trusting of controlled substances purchased directly from pharmacies. Due to Mexico's limited opioid overdose surveillance infrastructure, the current death rate from these substances remains unknown.

Deimplementation in the provision of opioid agonist treatment to achieve equity of care for people engaged in treatment: a qualitative study

BACKGROUND

Deimplementation, the removal or reduction of potentially hazardous approaches to care, is key to progressing social equity in health. While the benefits of opioid agonist treatment (OAT) are well-evidenced, wide variability in the provision of treatment attenuates positive outcomes. During the COVID-19 pandemic, OAT services deimplemented aspects of provision which had long been central to treatment in Australia; supervised dosing, urine drug screening, and frequent in-person attendance for review. This analysis explored how providers considered social inequity in health of patients in the deimplementation of restrictive OAT provision during the COVID-19 pandemic.

METHODS

Between August and December 2020, semi-structured interviews were conducted with 29 OAT providers in Australia. Codes relating to the social determinants of client retention in OAT were clustered according to how providers considered deimplementation in relation to social inequities. Normalisation Process Theory was then used to analyse the clusters in relation to how providers understood their work during the COVID-19 pandemic as responding to systemic issues that condition OAT access.

RESULTS

We explored four overarching themes based on constructs from Normalisation Process Theory: adaptive execution, cognitive participation, normative restructuring, and sustainment. Accounts of adaptive execution demonstrated tensions between providers' conceptions of equity and patient autonomy. Cognitive participation and normative restructuring were integral to the workability of rapid and drastic changes within the OAT services. Key transformative actors included communities of practice and "thought leaders" who had long supported deimplementation for more humane care. At this early stage of the pandemic, providers had already begun to consider how this period could inform sustainment of deimplementation. When considering a future, post-pandemic period, several providers expressed discomfort at operating with "evidence-enough" and called for narrowly defined types of data on adverse events (e.g. overdose) and expert consensus on takeaway doses.

CONCLUSIONS

The possibilities for achieving social equity in health are limited by the divergent treatment goals of providers and people receiving OAT. Sustained and equitable deimplementation of obtrusive aspects of OAT provision require co-created treatment goals, patient-centred monitoring and evaluation, and access to a supportive community of practice for providers.

"A lotta people switched playing hard ball to playing Russian roulette": 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. Interviews explored overdose experiences and changes in the drug supply. Thematic analysis of coded interview transcripts explored overdose experiences, perspectives on drug supply changes, interactions with harm reduction services, and naloxone access.

Results

Among 28 participants, 13 had experienced an overdose. Participants discussed rising levels of fentanyl in local drug supplies and increasing overdose incidents in their social networks. Participants discussed a general shift from injecting heroin to smoking fentanyl in their networks. Participants' most common concerns included having consistent access to a safe and potent drug supply and naloxone.

Conclusion

Participants prioritized adapting to drug supply changes and preventing overdose compared to other health concerns, such as HIV and COVID-19. Efforts to address overdose in this region could benefit from drug checking services and expanded, equitable delivery of naloxone.

Fentanyl, Heroin, and Methamphetamine-Based Counterfeit Pills Sold at Tourist-Oriented Pharmacies in Mexico: An Ethnographic and Drug Checking Study

Background

Our ethnographic team has conducted longitudinal research focused on illicit drug markets in Northern Mexico since 2018. In 2021-2022, study participants described the arrival of new, unusually potent tablets sold as ostensibly controlled substances, without a prescription, directly from pharmacies that cater to US tourists. Concurrently, fentanyl- and methamphetamine-based counterfeit prescription drugs have driven escalating overdose death rates in the US, however their presence in Mexico has not been assessed.

Aims

To characterize the availability of counterfeit and authentic controlled substances at pharmacies in Northern Mexico available to English-speaking tourists without a prescription.

Methods

We employed an iterative, exploratory, mixed methods design. Longitudinal ethnographic data was used to characterize tourist-oriented micro-neighborhoods and guide the selection of n=40 pharmacies in n=4 cities in Northern Mexico. In each pharmacy, samples of "oxycodone", "Xanax", and "Adderall" were sought as single pills, during English-language encounters, after which detailed ethnographic accounts were recorded. We employed immunoassay-based testing strips to check each pill for the presence of fentanyls, benzodiazepines, amphetamines, and methamphetamines. We used Fourier-Transform Infrared Spectroscopy to further characterize drug contents.

Results

Of 40 pharmacies, these controlled substances could be obtained in any form with no prescription at 68.3% and as single pills at 46.3%. Counterfeit pills were obtained at n=11 (26.8%) of pharmacies. Of n=45 samples sold as one-off controlled substances, n=20 were counterfeit including 9 of 11 (81.8%) of samples sold as "Adderall" that contained methamphetamine, and 8 of 27 (29.6%) of samples sold as "Oxycodone" that contained fentanyl, and n=3 'Oxycodone' samples containing heroin. Pharmacies providing counterfeit drugs were uniformly located in tourist-serving micro-neighborhoods, and generally featured English-language advertisements for erectile dysfunction medications and 'painkillers'. Pharmacy employees occasionally expressed concern about overdose risk and provided harm reduction guidance.

Discussion

The availability of fentanyl-, heroin-, and methamphetamine-based counterfeit medications in Northern Mexico represents a public health risk, and occurs in the context of 1) the normalization of medical tourism as a response to rising unaffordability of healthcare in the US, 2) plummeting rates of opioid prescription in the US, affecting both chronic pain patients and the availability of legitimate pharmaceuticals on the unregulated market, 3) the rise of fentanyl-based counterfeit opioids as a key driver of the fourth, and deadliest-to-date, wave of the opioid crisis. It is not possible to distinguish counterfeit medications based on appearance, because identically-appearing authentic and counterfeit versions are often sold in close geographic proximity. Nevertheless, US tourist drug consumers may be more trusting of controlled substances purchased directly from pharmacies. Due to Mexico's limited opioid overdose surveillance infrastructure, the current death rate from these substances remains unknown.

Modelling the contribution of incarceration and public health oriented drug law reform to HCV transmission and elimination among PWID in Tijuana, Mexico

BACKGROUND

Incarceration is associated with increased risk of hepatitis C virus (HCV) among people who inject drugs (PWID). Mexico's previous attempt in implementing a public health-oriented drug law reform resulted in minimal impact on incarceration among PWID. However, implementation of reforms alongside Mexico's HCV elimination program has the potential to reshape the HCV epidemic among PWID in the next decade. We use data from a cohort of PWID in Tijuana, Mexico, to inform epidemic modeling to assess the contribution of incarceration and fully implemented drug reform on HCV transmission and elimination among PWID.

METHODS

We developed a dynamic, deterministic model of incarceration, HCV transmission and disease progression among PWID. The model was calibrated to data from Tijuana, Mexico, with 90% HCV seroprevalence among 10,000 PWID. We estimated the 10-year population attributable fraction (PAF) of incarceration to HCV incidence among PWID and simulated, from 2022, the potential impact of the following scenarios: 1) decriminalization (80% reduction in incarceration rates); 2) fully implemented drug law reform (decriminalization and diversion to opiate agonist therapy [OAT]); 3) fully implemented drug law reform with HCV treatment (direct-acting antivirals [DAA]). We also assessed the number DAA needed to reach the 80% incidence reduction target by 2030 under these scenarios.

RESULTS

Projections suggest a PAF of incarceration to HCV incidence of 5.4% (95% uncertainty interval [UI]:0.6-11.9%) among PWID in Tijuana between 2022-2032. Fully implemented drug reforms could reduce HCV incidence rate by 10.6% (95%UI:3.1-19.2%) across 10 years and reduce the number of DAA required to achieve Mexico's HCV incidence reduction goal by 14.3% (95%UI:5.3-17.1%).

CONCLUSIONS

Among PWID in Tijuana, Mexico, incarceration remains an important contributor to HCV transmission. Full implementation of public health-oriented drug law reform could play an important role in reducing HCV incidence and improve the feasibility of reaching the HCV incidence elimination target by 2030.

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.

RESULTS

Of 612 PWID, most were male (74.0 %), Latinx (71.9 %), US residents (67.0 %). Mean age was 43 years. In the last six months, 15.8 % experienced overdose, 31.0 % knowingly used fentanyl and 11.1 % used china white, of whom 77.9 % did not think it contained fentanyl. After controlling for sex and race, factors independently associated with risk of overdose included knowingly using fentanyl, using china white and not believing it contained fentanyl, recent drug rehabilitation, being stopped/arrested by police, and homelessness. Further, PWID who believed china white contained fentanyl were less likely to use it.

CONCLUSIONS

Both intentional fentanyl use and unintentional exposure to fentanyl via china white were associated with overdose risk; however, PWID who believed china white contained fentanyl were less likely to use it. These data suggest that advanced drug checking systems should be implemented to empower PWID to avoid dangerous street formulations or to plan their drug use knowing its contents. Other overdose risk factors such as decreased tolerance following drug treatment, police interactions, and homelessness also require urgent intervention.