Skip to main content

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



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.


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.


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.


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.

Peer Review reports


Testing for SARS-CoV-2 infection is critical to identify cases who require quarantine and contact tracing, as well as treatment and supportive housing. Within the United States (U.S.), COVID-19 testing based on polymerase chain reaction (PCR) was made available at community clinics, pharmacies and laboratories since early in the pandemic [1]. However, PCR tests are expensive for those without health insurance as many sites do not provide free testing services, and turn-around times for results can take days. The nation’s first rapid at-home COVID-19 testing kit received emergency-use authorization in October, 2020 [2], but was not widely available in the U.S. for several months and often only available for a fee. In Mexico, free COVID-19 PCR tests are available at designated testing facilities or “fever clinics” for qualifying (i.e., symptomatic) individuals, and at private hospitals, laboratories or clinics for a fee [3, 4]. Despite efforts to increase the accessibility of COVID-19 testing, utilization remains low among racial/ethnic minorities and economically disadvantaged populations due to social and structural barriers related to health insurance, availability of testing sites, language, transportation, and misinformation [5,6,7,8,9].

COVID-19 testing misinformation (i.e., inaccurate information shared without malicious intent) and disinformation (i.e., deliberate spread of false information) have been negating efforts to increase COVID testing behaviors [10]. COVID-19 misinformation is a prominent barrier to testing among African American and Latinx communities [6, 11]. Research within the U.S. and United Kingdom has also highlighted connections between COVID-19 disinformation (e.g., conspiracy theories) and lower engagement in preventive behaviors (e.g., handwashing, mask wearing, and social distancing) and vaccination [12, 13]. In a previous analysis, COVID-19 disinformation was significantly associated with COVID-19 vaccine hesitancy among people who inject drugs (PWID) in the U.S.-Mexico border region [13]. However, it remains unknown if COVID-19 misinformation or disinformation impacts COVID-19 testing utilization among PWID.

Due to their high prevalence of chronic diseases [14], homelessness [15, 16], food insecurity [17], frequent incarceration [18, 19], and behavioral risk factors (e.g., engaging in sex work, sharing needles with others) [18], PWID are at elevated risk for SARS-CoV-2 infection and developing severe symptoms [14, 18, 20]. PWID often underutilize healthcare services due to stigma, discrimination, medical mistrust [21, 22], and mistreatment [15, 23, 24]. However, some PWID could receive COVID-19 testing through intersecting venues or touchpoints including substance use disorder (SUD) treatment programs, syringe service programs (SSPs), emergency rooms, and jail/prisons [25,26,27,28].

We identified correlates of COVID-19 testing and described interactions with services or venues where COVID-19 testing could have been offered, drawing from literature on overdose prevention ‘touchpoints’ within the healthcare system [29]. We hypothesized that socio-structural determinants (e.g., food/housing insecurity, Latinx ethnicity), and COVID-19 disinformation and misinformation would be associated with less COVID-19 testing. We also hypothesized that PWID with chronic health conditions and those who had recently been incarcerated or received health care services would be more likely to have had a COVID-19 test.


Participants and eligibility

Between October 28, 2020 and September 10, 2021, people aged ≥18 or older who injected drugs within the last month and lived in San Diego County or Tijuana were recruited through street outreach, as previously described [18]. Recruitment took place using a recreational vehicle whereby potential participants were approached by outreach workers in various locations, such as on the street, parks, shelters, motels, river canyons and vacant lots. All participants provided written informed consent. Protocols were approved by the Human Research Protection Program at the University of California San Diego and institutional review board at Xochicalco University in Tijuana. The study was conducted in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki).

Survey measures

Participants underwent face-to-face interviewer-administered questionnaires using computer assisted personal interviews. To reduce participant burden, some survey items were administered at baseline and approximately one week later for which they were compensated $20 USD and $10 USD, respectively. Surveys assessed socio-demographics, number of hours spent on the street on a typical day over the past 6 months (including looking for drugs, obtaining money or sleeping), injection and non-injection use of specific drugs (ever and in the last six months), chronic health problems (e.g., diabetes, asthma, hypertension), food insecurity [30], COVID-19 experiences (negative income impact/food insecurity, knows someone who died from COVID), COVID-19 exposures, and protective behaviors (e.g., social distancing, masking). Generalized anxiety disorder symptoms were assessed through the GAD-7 [31, 32], which demonstrated high internal reliability in the current study (α = 0.93, ω = 0.78). Perceived threat of COVID-19 was assessed by asking how worried they were about getting COVID-19 (or getting it again) on a ten point scale [33].

Participants were asked if they had ever received a COVID-19 test, and if so, to specify the date, location and result (if known). We also inquired about encounters with potential COVID-19 testing touchpoints (i.e., where COVID-19 testing could have been offered) in the last six months [29]. These included being enrolled in a SUD treatment program, having been incarcerated, sleeping in a shelter, using a SSP, having an overdose, or having been tested for HIV or HCV since the COVID-19 epidemic began.

To assess COVID-19 misinformation, we presented participants with seven statements about SARS-CoV-2 transmission, severity, immunity, symptoms, treatments and vaccines and asked them to classify each statement as “True”, “False,” or “Unsure” [13]. These included the following: (1) COVID-19 cannot be easily spread from one person to another; (2) many thousands of people have not died from COVID-19; (3) most people are immune to COVID-19; (4) you can tell someone has COVID-19 from looking at them; (5) there are treatments that can cure COVID-19; and (6) COVID-19 is about as dangerous as having the flu. We then created a binary variable for each statement indicating whether the participant was misinformed or not.

COVID-19 disinformation was assessed through a six-item scale including conspiracy theory items as previously described [13]. These included “COVID-19 was created by the pharmaceutical industry” or “the Chinese government”, “childhood vaccines cause autism” [34], as well as three additional items: “COVID-19 vaccines include a tracking device”, “alter DNA”, and “COVID-19 vaccines offered to ‘people like me’ are not as safe”. We dichotomized responses to indicate endorsement of disinformation (“True” and “Unsure”) or not (“False”) and summed them into a total score ranging from 0 to 6. Cronbach’s alpha and McDonald’s omega were 0.78. The mean inter-item correlation value was 0.31, which indicates optimal internal consistency [35].

SARS-CoV-2 antibody detection

Blood samples were collected by venipuncture. Serums were batched and tested weekly by Genalyte® (San Diego, CA), using their Maverick™ Multi-Antigen Serology Panel [36] that detects IgG and IgM antibodies to five SARS-CoV-2 antigens. A machine learning algorithm was used to call results using the Random Forest Ensemble method with 3000 decision trees [37].

HIV and HCV serology

Rapid HIV and HCV tests were conducted using the Miriad® HIV/HCV Antibody InTec Rapid Anti-HCV Test (Avantor, Radnor, PA). Reactive and indeterminate tests underwent a second rapid test with Oraquick® HIV or Oraquick® HCV, respectively (Orasure, Bethlehem, PA) and were confirmed by Western Blot at the UC San Diego Centers for AIDS Research.

Statistical analysis

The outcome for this analysis was reporting having had a COVID-19 test prior to joining the study (yes/no). Characteristics of participants who had a COVID-19 test versus those who had not were compared using Mann-Whitney U tests for continuous variables and Chi-square tests or Fisher’s exact tests for categorical variables. Univariate and multivariable logistic regressions with robust standard error estimation via generalized estimating equations were performed to identify factors associated with COVID-19 testing.

Variables attaining significance at α = 0.10 in univariate regression models were considered candidates for inclusion in multivariable models, using Hosmer and Lemeshow’s purposeful selection of variables approach [38] to arrive at a final model. Variables were retained in the final multivariable model based on statistical significance and relationships among potential predictors (e.g., correlations, confounding, and interactions). Since availability of COVID-19 testing may have changed during the 11 month study period, we included a linear term representing the time that had elapsed since the interview. Since there was no interaction by site (i.e., residence in San Diego versus Tijuana), we did not stratify by place of residence. All statistical analyses were conducted using SAS, version 9.4.


Sample characteristics and COVID-19 testing history

A total of 583 participants who completed baseline and supplemental interviews and responded to questions about COVID-19 testing history were included in this analysis. The majority identified as male (74.3%) and Hispanic, Latinx, or Mexican (73.6%) and 37.7% had completed high school or its equivalent. By design, approximately half (58.7%) resided in San Diego County (Table 1). Mean age was 43 years (standard deviation [SD]: 11).

Table 1 Characteristics Associated with COVID-19 Testing among PWID in San Diego, CA and Tijuana, Mexico (N = 583)

In the past six months, 43.7% of participants were homeless. The majority injected heroin (87.7%), methamphetamine (47.3%) or fentanyl (20.2%) in the last six months. Most had also smoked, snorted or inhaled or methamphetamine (63.1%), heroin (26.8%), fentanyl (18.5%) or cocaine (11.1%) in the last six months. Over one third tested HCV-seropositive (38.9%), 7.9% tested HIV-seropositive and 36.2% reported at least one other chronic health condition (e.g., diabetes, hypertension).

Overall, 178 participants (30.5%) reported that they previously had a COVID-19 test. Of 105 participants who were asked the location of their COVID-19 test in a supplemental survey, the most common testing locations were community clinics (including mobile clinics and health fairs; 55.2%), hospitals (14.3%), doctors’ offices (14.3%), jail/prison/detention centers (10.5%), SSPs (5.7%), SUD treatment clinics (2.9%), and pharmacies (1.9%).

Considering potential touchpoints for COVID-19 testing, 40% had received an HIV or HCV test outside of the study since the COVID-19 epidemic began. In the last 6 months, 15% had an overdose, 10% had been incarcerated, 7.2% slept in a shelter or a welfare residence, 8.6% had visited a SUD treatment program and 2.4% had used a SSP. Of the 405 participants who had not had a prior COVID-19 test, almost half (46%) reported at least one touchpoint encounter where COVID-19 testing could have been offered. Furthermore, of 571 participants who provided blood samples for SARS-CoV-2 serology and who tested seropositive in our study (N = 172, 30.1%), 70.9% had not previously had a COVID-19 test and 50.3% had encounters with at least one touchpoint where COVID-19 testing could have been offered.

Factors associated with COVID-19 testing in bivariate analysis

Sociodemographic Factors. Compared to those who had not had a prior COVID-19 test, those who had been tested were more likely to be living in San Diego County (versus Tijuana) and were less likely to identify as Hispanic, Latinx or Mexican. COVID-19 testing was positively associated with having completed high school or its equivalent and being homeless in the last six months (Tables 1 and 2).

Table 2 Factors associated with SARS-CoV-2 testing in Tijuana and San Diego

Behavioral and Substance Use Factors. Behaviors significantly associated with higher odds of COVID-19 testing included non-injection use of fentanyl or injecting methamphetamine in the last six months and spending more time on the street.

Mental Health and Attitudinal Factors. Increased anxiety reflected by higher GAD-7 scores and expressing greater worry about COVID-19 were associated with higher odds of COVID-19 testing.

COVID-19 Misinformation and Disinformation. Endorsing most statements reflecting COVID-19 misinformation or disinformation were not significantly associated with a lower odds of COVID-19 testing with the exception of believing that the coronavirus was created by the Chinese government as a biological weapon.

Health-related Factors. Having diabetes, at least one chronic condition, ever having had a flu vaccine and testing HCV or HIV seropositive were significantly associated with COVID-19 testing.

COVID-19 Related Factors and Protective Behaviors. Using facemasks, practicing social distancing, having received at least one COVID-19 vaccine dose, and having been exposed to someone with COVID-19 were significantly associated with COVID-19 testing. Having primarily obtaining their COVID-19 information from social media or health providers was significantly associated with higher odds of COVID-19 testing, whereas obtaining most of their COVID-19 information from friends was inversely associated with COVID-19 testing.

Touchpoints for COVID-19 Testing. Having been incarcerated, overdosed, slept in a shelter, received SUD treatment or visited a SSP program in the last six months were significantly associated with higher odds of COVID-19 testing.

Factors associated with COVID-19 testing in multivariate analysis

Factors Independently Associated with COVID-19 Testing. Our final multivariate model reflecting factors that were independently associated with COVID-19 testing while controlling for time is displayed in Table 3. Living in San Diego County (versus Tijuana), and having been incarcerated or enrolled in a SUD treatment program in the last six months were independently associated with COVID-19 testing. Having at least one chronic condition, receiving at least one COVID-19 vaccine dose, having been homeless or using fentanyl by means other than injection in the last six months were also independently associated with having had a COVID-19 test. Having been tested for HIV or HCV since the COVID-19 epidemic began remained marginally associated with COVID-19 testing.

Table 3 Factors Independently Associated with COVID-19 Testing among PWID in San Diego, CA and Tijuana, Mexico


We identified several factors that were independently associated with COVID-19 testing among PWID in the Mexico-US border region, as well as multiple touchpoints where COVID-19 testing could have been offered. Although SARS-CoV-2 prevalence among PWID in San Diego County and Tijuana is higher than that of the general population in either city [18], less than one third of our sample had ever been tested for COVID-19. Of concern, over two thirds of participants who tested SARS-CoV-2 seropositive in our study had not previously had a COVID-19 test and half reported at least one missed opportunity for testing. Our findings are consistent with a study of individuals who currently and formerly used drugs in Baltimore, Maryland, which found that only 13% had received a COVID-19 test in the first quarter of the pandemic [16]. Similarly, in a study of PWID in England and Northern Ireland conducted in 2020, only 22% had ever had a COVID-19 test [39]. These findings have implications for improving service delivery for this vulnerable population, as well as broader efforts to reduce SARS-CoV-2 transmission and morbidity and mortality in marginalized communities.

An encouraging finding was that PWID who reported receiving SUD treatment were more likely to have been tested for COVID-19. This is supported by data from a recent study of 265 clients receiving residential SUD treatment in Southern California, among whom 74% had received a COVID-19 test [26]. Although it is not clear whether or not individuals had received testing at the SUD program itself or whether SUD treatment was a marker for health-seeking behaviors, some participants did report having had a COVID-19 test at SUD treatment clinics in our study. SUD treatment programs could serve as an ideal venue for providing COVID-19 testing as well as vaccines and education to dispel myths about COVID-19 testing and vaccination. However, during the pandemic, some SUD treatment programs were suspended or only offered take-home or telemedicine services [40], potentially reducing opportunities for the provision of other services.

We also found that recent incarceration was associated with more than a two-fold higher odds of having had a COVID-19 test. Indeed, one in ten individuals who had a prior COVID-19 test reported that they obtained the test in a jail, prison or detention center. In many of these cases, COVID-19 testing may have been mandatory, since COVID-19 outbreaks have been reported in correctional facilities in California and elsewhere [41] and incarceration was independently associated with SARS-CoV-2 seropositivity among PWID in our study sample [18]. These outbreaks prompted mass SARS-CoV-2 testing in some jurisdictions [25]. A study conducted in 2020 among the U.S. Federal Bureau of Prisons found that half of the prison populace had been subjected to COVID-19 testing [42].

As expected, PWID who were already in contact with the healthcare system were more likely to have had a COVID-19 test. Specifically, those who had been tested for HIV or HCV since the COVID-19 epidemic began, and those who had received at least one COVID-19 vaccine dose were significantly more likely to have had a COVID-19 test. Furthermore, those who had at least one chronic condition were more likely to receive COVID-19 testing, which is noteworthy since individuals with co-morbidities are at greater risk of developing serious complications associated with COVID-19 [14].

Our findings that homelessness and non-injection use of fentanyl (e.g., smoked, snorted, inhaled, vaped) were both independently associated with having a COVID-19 test was surprising. However, this could be explained by concerted efforts in both San Diego and Tijuana to provide outreach to people experiencing homelessness during the COVID-19 pandemic, for example, through health fairs, mobile testing units and temporary housing. Similarly, individuals who report using fentanyl likely had greater addiction severity and may have been more likely to come into contact with community-based health providers who offered COVID-19 testing. Compared to other illicit substances, fentanyl is a highly potent drug with heightened risks for experiencing an overdose [43], which may have led to increased contact with medical settings (e.g., Emergency Departments) [44] and subsequently COVID-19 testing. These interpretations are speculative and deserve greater attention. Kral and colleagues have documented marked transitions from injection of black tar heroin to non-injection use of fentanyl in San Francisco [45] and this sub-group of substance users may be more attuned to their health.

Contrary to expectation, we did not find that Latinx ethnicity was associated with a lower odds of COVID-19 testing; however, ethnicity was highly correlated with place of residence. We did not find that COVID-19 disinformation or misinformation were significantly associated with a reduced odds of COVID-19 testing after controlling for other factors, perhaps because these measures were not specific to COVID-19 testing. Future studies may benefit by incorporating tailored measures on COVID-19 disinformation and misinformation that specifically address COVID testing which should be informed by qualitative research to more fully assess the influence of these factors on COVID-19 testing behaviors.

The lack of affordable and accessible rapid COVID-19 testing has been a major shortfall of the public health response to the pandemic in the United States, Mexico [9, 46, 47], and elsewhere. Considering that over half of our participants earned less than $500 USD per month and the prevalence of homelessness was high, it is unreasonable to expect that this population would have access to financial or transportation resources (or sufficient access to the Internet) to be able to purchase expensive at-home test kits or make and attend appointments for COVID-19 testing. To reduce high rates of morbidity and mortality due to COVID-19 and ongoing SARS-CoV-2 transmission, it is critical that infections among PWID and other vulnerable populations are detected early, especially given their high prevalence of SARS-CoV-2 infection [18]. Efforts to expand free rapid testing for PWID at venues they already access and trust are especially needed, given recent evidence suggesting that people with SUD may be more prone to breakthrough infections following vaccination due to their high prevalence of co-morbidities [48].


This study was limited by the cross-sectional nature of the analysis, which prevented us from drawing causal inferences. Although this was a binational study, sampling was non-random and our findings may not generalize to other PWID populations. Our reliance on self-report may have led to socially desirable responding or problems with recall. We were unable to differentiate between situations where COVID-19 testing was mandatory versus situations in which testing was voluntary and sought out by participants. For example, COVID-19 testing was likely required for participants entering correctional facilities and may also have been mandatory in some shelters. Similarly, we did not ask participants if they were required to pay for COVID-19 testing. Since both the availability and the cost of COVID-19 testing may have changed during the pandemic, we controlled for time in our analysis. It should be also noted that after study recruitment concluded, at-home tests became freely available from the U.S. government [49] in January 2022. However, access to government distributed at-home testing kits may still pose access difficulties for some populations, such as those who are unstably housed or people with low health literacy.

Some associations may not have been detected due to low statistical power. For example, the lack of an association between COVID-19 testing and attending SSPs was likely due to the small number of participants who had recently accessed these programs, since service provision for some harm reduction programs across the U. S was compromised during the pandemic [27, 50].


Although SARS-CoV-2 seroprevalence among PWID in San Diego County and Tijuana was higher than the general population in their respective cities, we found that over two thirds of those seropositive for SARS-CoV-2 had never had a prior COVID-19 test. Notably, half reported at least one touchpoint encounter where they could have received COVID-19 testing but did not. Our participants were more likely to have had prior COVID-19 testing if they had received care for a comorbid health condition, had been tested for HIV or HCV, recently received treatment for SUD or if they had been incarcerated. Given the overall low level of COVID-19 testing and numerous missed opportunities for testing, our findings highlight the urgent need to improve access to free rapid COVID-19 tests in venues that PWIDs trust and routinely access. Such initiatives may also improve uptake of COVID-19 vaccines.

Availability of data and materials

The datasets generated and/or analysed during the current study are not publicly due to the fact that the study team is still collecting data until August 31st, 2023, but data are available from the corresponding author on reasonable request. For more information, please contact Steffanie Strathdee, Ph.D. at



People Who Inject Drugs


Substance Use Disorder


Syringe Sharing Program


  1. Centers for Disease Control and Prevention. CDC’s Diagnostic Test for COVID-19 Only and Supplies. 2021. Accessed 14 Dec 2021.

  2. Shuren JE. Coronavirus (COVID-19) Update: FDA Authorizes Additional OTC Home Test to Increase Access to Rapid Testing for Consumers. 2021. Accessed 29 Nov 2021.

  3. Gobierno de México. COVID-19. 2021. Accessed 29 Nov 2021.

  4. Secretariat of Health [Salud]. Laboratorios de pruebas acreditados y aprobados. 2018. Accessed 29 Nov 2021.

  5. Millett GA, Jones AT, Benkeser D, Baral S, Mercer L, Beyrer C, et al. Assessing differential impacts of COVID-19 on black communities. Ann Epidemiol. 2020;47:37–44.

    Article  Google Scholar 

  6. Bateman LB, Schoenberger YM, Hansen B, Osborne TN, Okoro GC, Speights KM, et al. Confronting COVID-19 in under-resourced, African American neighborhoods: a qualitative study examining community member and stakeholders' perceptions. Ethn Health. 2021;26(1):49–67.

    Article  Google Scholar 

  7. Karaye IM, Horney JA. The impact of social vulnerability on COVID-19 in the U.S.: an analysis of spatially varying relationships. Am J Prev Med. 2020;59(3):317–25.

    Article  Google Scholar 

  8. Jacobson M, Chang TY, Shah M, Pramanik R, Shah SB. Racial and ethnic disparities in SARS-CoV-2 testing and COVID-19 outcomes in a Medicaid managed care cohort. Am J Prev Med. 2021;61(5):644–51.

    Article  Google Scholar 

  9. Grigsby-Toussaint DS, Shin JC, Jones A. Disparities in the distribution of COVID-19 testing sites in black and Latino areas in new York City. Prev Med. 2021;147:106463.

    Article  Google Scholar 

  10. Swire-Thompson B, Lazer D. Public health and online misinformation: challenges and recommendations. Annu Rev Public Health. 2020;41:433–51.

    Article  Google Scholar 

  11. Cervantes L, Martin M, Frank MG, Farfan JF, Kearns M, Rubio LA, et al. Experiences of Latinx individuals hospitalized for COVID-19: a qualitative study. JAMA Netw Open. 2021;4(3):e210684.

    Article  Google Scholar 

  12. Imhoff R, Lamberty P. A bioweapon or a hoax? The link between distinct conspiracy beliefs about the coronavirus disease (COVID-19) outbreak and pandemic behavior. Soc Psychol Personal Sci. 2020;11(8):1110–8.

    Article  Google Scholar 

  13. Strathdee SA, Abramovitz D, Harvey-Vera AY, Vera CF, Rangel G, Artamonova I, et al. Correlates of COVID-19 vaccine hesitancy among people who inject drugs in the San Diego-Tijuana border region. Clin Infect Dis. 2021;ciab975 In Press.

  14. Wang QQ, Kaelber DC, Xu R, Volkow ND. COVID-19 risk and outcomes in patients with substance use disorders: analyses from electronic health records in the United States. Mol Psychiatry. 2021;26(1):30–9.

    Article  CAS  Google Scholar 

  15. Vasylyeva TI, Smyrnov P, Strathdee S, Friedman SR. Challenges posed by COVID-19 to people who inject drugs and lessons from other outbreaks. J Int AIDS Soc. 2020;23(7):e25583.

    Article  CAS  Google Scholar 

  16. Genberg BL, Astemborski J, Piggott DA, Woodson-Adu T, Kirk GD, Mehta SH. The health and social consequences during the initial period of the COVID-19 pandemic among current and former people who inject drugs: a rapid phone survey in Baltimore, Maryland. Drug Alcohol Depend. 2021;221:108584.

    Article  CAS  Google Scholar 

  17. Rouhani S, Allen ST, Whaley S, White RH, O'Rourke A, Schneider KE, et al. Food access among people who inject drugs in West Virginia. Harm Reduct J. 2021;18(1):90.

    Article  Google Scholar 

  18. Strathdee SA, Abramovitz D, Harvey-Vera A, Vera CF, Rangel G, Artamonova I, et al. Prevalence and correlates of SARS-CoV-2 seropositivity among people who inject drugs in the San Diego-Tijuana border region. PLoS One. 2021;16(11):e0260286.

    Article  CAS  Google Scholar 

  19. Reinhart E, Chen DL. Incarceration and its disseminations: COVID-19 pandemic lessons from Chicago’s Cook County jail: study examines how arrest and pre-trial detention practices may be contributing to the spread of COVID-19. Health Aff. 2020;39(8):1412–8.

    Article  Google Scholar 

  20. Hiller-Sturmhoefel S. People With SUDs Have Increased Risk for COVID-19 and Worse Outcomes. 2021. Accessed 9 Dec 2021.

  21. Aronson ID, Bennett AS, Ardouin-Guerrier MA, Rivera-Castellar G, Gibson B, Santoscoy S, et al. How vaccine ambivalence can lead people who inject drugs to decline COVID-19 vaccination, and ways this can be addressed: a qualitative study. JMIR Form Res. 2022;6(3):e35066.

    Article  Google Scholar 

  22. Motavalli D, Taylor JL, Childs E, Valente PK, Salhaney P, Olson J, et al. "health is on the Back burner:" multilevel barriers and facilitators to primary care among people who inject drugs. J Gen Intern Med. 2021;36(1):129–37.

    Article  Google Scholar 

  23. Paquette CE, Syvertsen JL, Pollini RA. Stigma at every turn: health services experiences among people who inject drugs. Int J Drug Policy. 2018;57:104–10.

    Article  Google Scholar 

  24. Biancarelli DL, Biello KB, Childs E, Drainoni M, Salhaney P, Edeza A, et al. Strategies used by people who inject drugs to avoid stigma in healthcare settings. Drug Alcohol Depend. 2019;198:80–6.

    Article  Google Scholar 

  25. Hagan LM, Williams SP, Spaulding AC, Toblin RL, Figlenski J, Ocampo J, et al. Mass testing for SARS-CoV-2 in 16 prisons and jails - six jurisdictions, United States, April-may 2020. MMWR Morb Mortal Wkly Rep. 2020;69(33):1139–43.

    Article  CAS  Google Scholar 

  26. Masson CL, McCuistian C, Straus E, Elahi S, Chen M, Gruber VA, et al. COVID-19 vaccine trust among clients in a sample of California residential substance use treatment programs. Drug Alcohol Depend. 2021;225:108812.

    Article  CAS  Google Scholar 

  27. Glick SN, Prohaska SM, LaKosky PA, Juarez AM, Corcorran MA, Des Jarlais DC. The impact of COVID-19 on syringe services programs in the United States. AIDS Behav. 2020;24(9):2466–8.

    Article  Google Scholar 

  28. Ochalek TA, Cumpston KL, Wills BK, Gal TS, Moeller FG. Nonfatal opioid overdoses at an urban emergency department during the COVID-19 pandemic. JAMA. 2020;324(16):1673–4.

    Article  CAS  Google Scholar 

  29. Larochelle MR, Bernstein R, Bernson D, Land T, Stopka TJ, Rose AJ, et al. Touchpoints - opportunities to predict and prevent opioid overdose: a cohort study. Drug Alcohol Depend. 2019;204:107537.

    Article  CAS  Google Scholar 

  30. U.S. Department of Agriculture. Food Security in the U.S. - Measurement. 2021. Accessed 8 Oct 2021.

  31. Spitzer RL, Kroenke K, Williams JB, Lowe B. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092–7.

    Article  Google Scholar 

  32. Lowe B, Decker O, Muller S, Brahler E, Schellberg D, Herzog W, et al. Validation and standardization of the generalized anxiety disorder screener (GAD-7) in the general population. Med Care. 2008;46(3):266–74.

    Article  Google Scholar 

  33. Gorbach PM, Siminski S, Ragsdale A, Investigators CP. Cohort profile: the collaborating consortium of cohorts producing NIDA opportunities (C3PNO). Int J Epidemiol. 2021;50(1):31–40.

    Article  Google Scholar 

  34. Romer D, Jamieson KH. Conspiracy theories as barriers to controlling the spread of COVID-19 in the U.S. Soc Sci Med. 2020;263:113356.

    Article  Google Scholar 

  35. Briggs SR, Cheek JM. The role of factor analysis in the development and evaluation of personality scales. J Pers. 1986;54(1):106–48.

    Article  Google Scholar 

  36. Food and Drug Administration (FDA). Maverick™ SARS-CoV-2 Multi-Antigen Serology Panel v2 01030ART-01. Accessed 16 June 2021.

  37. Ikegami S, Benirschke RC, Fakhrai-Rad H, Motamedi MH, Hockett R, David S, et al. Target specific serologic analysis of COVID-19 convalescent plasma. PLoS One. 2021;16(4):e0249938.

    Article  CAS  Google Scholar 

  38. Hosmer D, Lemeshow S. Applied survival analysis: regression modeling of time to event data. New York: Wiley-Interscience; 1999.

    Google Scholar 

  39. Croxford S, Emanuel E, Ibitoye A, Njoroge J, Edmundson C, Bardsley M, et al. Preliminary indications of the burden of COVID-19 among people who inject drugs in England and Northern Ireland and the impact on access to health and harm reduction services. Public Health. 2021;192:8–11.

    Article  CAS  Google Scholar 

  40. Nesoff ED, Marziali ME, Martins SS. The estimated impact of state-level support for expanded delivery of substance use disorder treatment during the COVID-19 pandemic. Addiction. 2021. Epub ahead of print.

  41. Wallace M, Hagan L, Curran KG, Williams SP, Handanagic S, Bjork A, et al. COVID-19 in correctional and detention facilities - United States, February-April 2020. MMWR Morb Mortal Wkly Rep. 2020;69(19):587–90.

    Article  CAS  Google Scholar 

  42. Toblin RL, Hagan LM. COVID-19 case and mortality rates in the Federal Bureau of Prisons. Am J Prev Med. 2021;61(1):120–3.

    Article  Google Scholar 

  43. Wilson N, Kariisa M, Seth P. Smith Ht, Davis NL: drug and opioid-involved overdose deaths - United States, 2017-2018. MMWR Morb Mortal Wkly Rep. 2020;69(11):290–7.

    Article  Google Scholar 

  44. Vivolo-Kantor AM, Seth P, Gladden RM, Mattson CL, Baldwin GT, Kite-Powell A, et al. Vital signs: trends in emergency department visits for suspected opioid overdoses - United States, July 2016-September 2017. MMWR Morb Mortal Wkly Rep. 2018;67(9):279–85.

    Article  Google Scholar 

  45. Kral AH, Lambdin BH, Browne EN, Wenger LD, Bluthenthal RN, Zibbell JE, et al. Transition from injecting opioids to smoking fentanyl in San Francisco, California. Drug Alcohol Depend. 2021;227:109003.

    Article  Google Scholar 

  46. Friedman J, Calderon-Villarreal A, Bojorquez I, Vera Hernandez C, Schriger DL, Tovar Hirashima E. Excess out-of-hospital mortality and declining oxygen saturation: the sentinel role of emergency medical services data in the COVID-19 crisis in Tijuana, Mexico. Ann Emerg Med. 2020;76(4):413–26.

    Article  Google Scholar 

  47. Mina MJ, Andersen KG. COVID-19 testing: one size does not fit all. Science. 2021;371(6525):126–7.

    Article  CAS  Google Scholar 

  48. Wang L, Wang Q, Davis PB, Volkow ND, Xu R. Increased risk for COVID-19 breakthrough infection in fully vaccinated patients with substance use disorders in the United States between December 2020 and august 2021. World Psychiatry. 2021;21(1):124–32.

    Article  Google Scholar 

  49. The White House Briefing Room. Fact Sheet: The Biden Administration to Begin Distributing At-Home, Rapid COVID-⁠19 Tests to Americans for Free, vol. 2022. Washington D.C.: The White House Statements and Releases; 2021.

  50. Bartholomew TS, Nakamura N, Metsch LR, Tookes HE. Syringe services program (SSP) operational changes during the COVID-19 global outbreak. Int J Drug Policy. 2020;83:102821.

    Article  Google Scholar 

Download references


The authors gratefully acknowledge the La Frontera study team and participants in San Diego and Tijuana and staff at Genalyte and Fluxergy for assistance interpreting laboratory results, laboratory staff at the Center for AIDS Research and Sharon Park for assistance with manuscript preparation.


This work was supported by the National Institute on Drug Abuse (NIDA) at the National Institutes of Health (NIH) (R01DA049644-S1, K01DA043412, T32DA023356 and RADxUP, R01 DA049644-02S2). Additional support was provided by the National Institute of Allergy and Infectious Diseases (P30 AI036214) and the Fogarty International Center (R21DA051951).

Author information

Authors and Affiliations



SY oversaw the analysis and wrote and edited the manuscript. SAS designed the study and most survey instruments, conceived of the research questions wrote and edited the manuscript. DA conducted the data analysis, prepared the results and edited the manuscript. GR helped design the study, oversaw data collection in Tijuana and edited the manuscript. AHV designed and pre-tested the survey, oversaw collection of laboratory specimens and edited the manuscript. CFV oversaw and participated in data collection in San Diego and edited the manuscript. IA programmed the study instrument, oversaw data management and edited the manuscript. ELB conducted the literature review and edited the manuscript. TP helped design the study and survey instruments and edited the manuscript. ARB helped interpret the analysis and wrote and edited the manuscript. LRS and ABA assisted with the design of survey instruments and edited the manuscript. The author(s) read and approved the final manuscript.

Corresponding author

Correspondence to Steffanie Ann Strathdee.

Ethics declarations

Ethics approval and consent to participate

This study was reviewed by the University of California San Diego Office of IRB Administration and the University of Xochicalco Institutional Review Board. All methods were carried out in accordance with relevant guidelines and regulations. Written informed consent was obtained from all participants of the study.

Consent for publication

Not applicable.

Competing interests

Authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yeager, S., Abramovitz, D., Harvey-Vera, A.Y. et al. A cross-sectional study of factors associated with COVID-19 testing among people who inject drugs: missed opportunities for reaching those most at risk. BMC Public Health 22, 842 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: