COVID-19 VACCINATION AMONG YOUNG PEOPLE WHO USE DRUGS IN VANCOUVER, CANADA

Abstract

Objectives

SARS-CoV-2 vaccines provide significant protection against severe illness and death from COVID-19, in addition to reducing community transmission. Emerging research has identified factors associated with vaccine uptake among adults who use drugs; however, less is known about youth and young adults who use drugs (YWUD). To address this gap, we sought to characterize factors associated with vaccine uptake and explore vaccine hesitancy among YWUD.

Methods

Data were derived from the At-Risk Youth Study, a prospective cohort of street-involved YWUD in Vancouver, Canada. Using multivariable logistic regression, we characterized factors associated with SARS-CoV-2 vaccine uptake between June and November 2021. Data on vaccine hesitancy were also collected.

Results

Among 301 participants enrolled in this study (median age: 29 [min and max: 20–40]), 151 (50.2%) self-reported receipt of at least one dose of a SARS-CoV-2 vaccine. In multivariable analysis, vaccine uptake was significantly associated with recent addiction treatment engagement (adjusted odds ratio [AOR] = 2.46, 95% confidence interval [CI]: 1.47–4.14) and receiving prescribed safer supply (e.g., opioids, stimulants) (AOR = 2.33, 95% CI: 1.03–5.62). Those who reported at least weekly crack use were significantly less likely to be vaccinated (AOR = 0.35, 95% CI: 0.12–0.92). The most reported reason for vaccine hesitancy was safety concerns, specifically regarding long-term side effects (27.4%).

Conclusion

Vaccine uptake was significantly lower among YWUD than adults who use drugs in Vancouver and the general population in British Columbia, among whom 75% and 93% received at least one dose during the same period. Study findings suggest connecting YWUD to healthcare and novel harm reduction interventions may increase vaccine uptake. Responses to vaccine hesitancy questions revealed complex perspectives of vaccines that were aligned with sources of vaccine hesitancy among the general population. Broader strategies combatting misinformation and promoting evidence-based vaccine information could be tailored to address the unique needs and barriers experienced by YWUD.

1. INTRODUCTION

The ongoing morbidity and mortality associated with the COVID-19 pandemic continues to be an important public health priority, particularly among marginalized populations such as people who use drugs (PWUD) who are at increased risk of SARS-CoV-2 infection and severe COVID-19 disease [1], [2]. In December 2020, many countries, including Canada and the United States (US), began providing SARS-CoV-2 vaccines to the general population [3], [4]. The SARS-CoV-2 vaccines provide significant protection against severe illness, hospitalization, and death from COVID-19, in addition to reducing community transmission [5].

In the study setting of Vancouver, Canada, vaccine rollout began in December 2020 with vaccines being provided to high-risk populations first (e.g., healthcare staff, long-term care residents) [6]. In February 2021 vaccine efforts expanded to include seniors aged 80+, Indigenous seniors aged 65 + and Elders, hospital staff, and vulnerable populations in select congregated settings [6]. From April to June 2021, vaccines became available to members of the general public aged 60–79 and anyone aged 16–69 who is considered to be clinically vulnerable [6]. Lastly, from July to September 2021, the rest of the general population from ages 18–59 were eligible to be vaccinated [6]. There were two types of vaccines available to BC residents at the time: Pfizer and Moderna mRNA vaccines. Later in 2021, the Janssen viral vector vaccine and the Novavax protein-based vaccine were also authorized for use and made available to residents [7]. The majority of the population received mRNA vaccines; however, individuals were generally not permitted to choose a preferred type of vaccine [8]. Two vaccine doses were administered 35 days apart in the early stages of the pandemic, to those who chose to be vaccinated [9]. Since the initial vaccination campaigns, the Government of BC subsequently made booster doses available to the general population. Vancouver Coastal Health employed a number of unique outreach efforts to reach marginalized populations living on the Downtown Eastside of Vancouver (DTES) (the lowest socioeconomic status neighbourhood in Canada), which resulted in high vaccine uptake among these residents (86 % have received two doses of a COVID-19 vaccine as of March 12, 2023) [10], [11], [12]. For example, at least three low-barrier drop-in vaccination clinics were run on a weekly basis in the DTES and cash stipends of $5 were provided to incentivize vaccine uptake without being high enough to be considered coercive [12], [13].

Examining vaccine uptake among PWUD is a priority as comorbidities associated with substance use may increase risks of experiencing negative health effects from contracting SARS-CoV-2 [14]. Additionally, there is an increased risk of transmission among this group as a result of high-risk substance use practices, including drug sharing, and living in congregate settings [15], [16], [17]. In the early waves of COVID-19, emergent research found that people with a substance use disorder (SUD) had an eight-fold increase in the odds of SARS-CoV-2 infection and people living with HIV had a two-fold increase in the hazard ratio of COVID-19 mortality [1], [2]. Emerging research has identified factors associated with vaccine uptake among adults who use drugs, such as receipt of addiction treatments, engagement with health services, and living with comorbidities [18], [19]. However, less is known about youth and young adults who use drugs (YWUD) who often experience barriers to healthcare access [20], [21], [22]. To address this gap, we sought to characterize the prevalence and factors associated with vaccine uptake and explore vaccine hesitancy among YWUD in Vancouver, Canada. Understanding factors associated with vaccine uptake and characterizing hesitancy can assist in targeting public health interventions for this unique population.

2. METHODS

Data for this study were derived from the At-Risk Youth Study (ARYS) (as opposed to a separate sub-study). ARYS is an ongoing prospective cohort of street-involved youth and young adults who use drugs (other than or in addition to cannabis) in Vancouver, Canada. To be eligible for enrolment in ARYS, participants had to be between the ages of 14–26 at the time of enrolment, reported unregulated drug use in the last month (e.g., cocaine, heroin, crack, crystal methamphetamine), be ‘street-involved’, defined as being without stable housing or accessing services for youth who are experiencing homelessness in the last month, and provide written informed consent.

Participants completed an interviewer-administered questionnaire at baseline and every six months thereafter. The questionnaire collected data on socio-demographics, substance use patterns and associated risks, income generation activities, and health and social service engagement. Participants received a $40 CAD honorarium at each study visit for their time and expertise. Additional details of the ARYS cohort have been published elsewhere [23]. The University of British Columbia/Providence Health Care Research Ethics Board has approved this study on an annual basis.

In response to the COVID-19 pandemic, all in-person data collection activities for ARYS were halted in March 2020. Public health and safety protocols were developed for the study procedures and the study instrument was revised to include items specific to the COVID-19 pandemic. Remote data collection resumed in July 2020, with follow-up study interviews conducted via telephone or videoconferencing. Participants were contacted via telephone, email, and/or social media to advise that they were due for a study follow-up visit. Those interested in participating could indicate their preference to have the interview conducted via telephone or videoconferencing. Participants were also asked at this time if they had access to a quiet and private space to conduct the interview and if they have access to a telephone or a smartphone/computer/tablet with internet access. Participants that did not have access to a telephone were provided with the option to use a study-owned pre-paid cell phone for the purpose of conducting the interview. Cell phones were picked up from the study office located in downtown Vancouver. Honorariums were forwarded via e-transfer for participants who had access to online banking. For those that did not have access to online banking, arrangements were made to pick up cash in person at the study office in accordance with public health measures.

All ARYS participants who completed an interview and answered the main outcome question between June and November 2021 were included in the present study. To assess the prevalence and correlates of vaccination against COVID-19 among YWUD, our primary outcome of interest was based on the question “Have you been vaccinated for COVID-19?” (yes vs. no). It was hypothesized that participants who are more connected to the health system would be more likely to have been vaccinated against COVID-19 since there may be reduced barriers to access or established relationships with healthcare professionals. Furthermore, we hypothesized that individuals who engage in high-intensity (e.g., weekly) drug use would be less likely to be vaccinated against COVID-19 since these individuals are more likely to experience barriers to accessing healthcare [24], [25]. We also included a range of socio-demographic, substance use and health and social service variables that we hypothesized to be potentially associated with COVID-19 vaccine uptake. These variables included: age (per year older); self-identified gender (men vs. women or other; this category included participants who identify as transgender, Two-Spirit, and those who preferred to self-describe in an ‘other’ category); race/ancestry (Black, Indigenous or Persons of Colour [BIPOC] vs. white); experiencing homelessness (yes vs. no); employment, defined as having a regular job, temporary work or self-employed (yes vs. no); self-reported belief of having ever been infected with the SARS-CoV-2 virus that causes COVID-19 (yes vs. no); previous receipt of annual influenza or flu shot (yes vs. no), based on the question “do you get an annual influenza or flu shot regularly?”. Those who responded “yes” and “sometimes” were coded as yes and those that responded “no” were coded as no; at least weekly drug injection (yes vs. no); at least weekly cocaine use (yes vs. no); at least weekly crack cocaine use (yes vs. no); at least weekly heroin/fentanyl/down use (yes vs. no); at least weekly crystal methamphetamine use (yes vs. no); at least weekly nonmedical prescription opioid (NMPO) use, defined as taking prescription opioids that were not prescribed or taking prescription opioids only for the experience or feeling they caused (yes vs. no); at least weekly cannabis use (yes vs. no); at least weekly alcohol use (yes vs. no); at least weekly tobacco use (yes vs. no); any drug or alcohol treatment, defined as having engaged with any drug or alcohol treatment programme, including detox, a recovery house, a treatment centre, a counsellor, Narcotics Anonymous/Cocaine Anonymous/Alcoholics/Anonymous/ SMART, opioid agonist therapy, out-patient treatment, or drug treatment court (yes vs. no); receipt of “prescribed safer supply” defined as receipt of selective pharmaceutical opioids and stimulants from a prescriber (physician or nurse practitioner) (yes vs. no); non-fatal overdose (yes vs. no); use of supervised injection or overdose prevention sites, defined as a designated space where staff provide on-site monitoring for people at risk of overdose and allow for rapid response when overdoses occur [26] (yes vs. no); and recent incarceration (yes vs. no). Except for gender and race/ancestry or unless otherwise specified, all variables referred to the six-month period before the interview.

As a first step, bivariate logistic regression analyses were utilized to determine factors associated with receipt of at least one dose of the SARS-CoV-2 vaccine. Variables that were significant at the p < 0.10 threshold in the bivariate analyses were entered into a multivariable logistic regression model. A backward elimination procedure was used to construct the multivariable model with the best fit, indicated by the lowest AIC value [27]. We utilized a conservative p-value of < 0.10 as the threshold for the inclusion of variables in the model-building process to ensure that all variables of potential importance were captured and included in the multivariable model.

Participants were also asked a series of questions related to vaccine hesitancy, including the reasons why they do not want to be vaccinated and probing questions to identify which conditions would promote vaccine confidence. We used descriptive statistics to summarize the data on vaccine hesitancy. All statistical analyses were performed using R (Version 4.2.2, R Foundation for Statistical Computing, Vienna, Austria). All p-values are two-sided with a significance threshold of 0.05.

3. RESULTS

Between June and November 2021, 302 participants completed a study visit and 301 were eligible and included in this analysis (response rate of 99.97%). In the study periods prior to the COVID-19 pandemic (June 2019-March 2020), 379 participants were seen for a follow-up visit. Despite the impact and disruption the COVID-19 pandemic had on study activities, 79.68% of participants who had a study visit before the onset of the COVID-19 pandemic were also seen for a follow-up visit during this study period (June-November 2021). The median age among the sample was 29 years (min–max: 20–39.5), 125 (41.5%) identified as women, transgender, Two-Spirit, or self-described in an ‘other’ category, and 120 (39.9%) identified as BIPOC. Overall, 151 (50.2%) participants reported having received at least one dose of a COVID-19 vaccine. Among these, 63 (20.9%) reported receiving one dose and 88 (29.2%) reported receiving two doses of a vaccine.

The characteristics of the study sample stratified by COVID-19 vaccine uptake and results from the bivariate analyses are presented in Table 1. In the bivariate analyses, age (odds ratio [OR] = 0.95 [95% Confidence Interval [CI]]: 0.90–1.00]); previous receipt of annual influenza or flu shot (OR = 1.76 [95% CI: 1.10–2.85]); at least weekly crack use (OR = 0.37 [95% CI: 0.13–0.95]); recent drug/alcohol treatment (OR = 3.00 [95 % CI: 1.87–4.87]); and receipt of prescribed safer supply (OR = 3.33 [95% CI: 1.60–7.46]) were all significantly associated with COVID-19 vaccine uptake (all p < 0.05). The results of the multivariable analysis are presented in Table 2. As shown, factors significantly positively associated with COVID-19 vaccine uptake included recent drug/alcohol treatment (adjusted odds ratio [AOR] = 2.46 [95% CI: 1.47–4.14]); and receipt of prescribed safer supply (AOR = 2.33 [95% CI: 1.03–5.62]). At least weekly crack use (AOR = 0.35 [95% CI: 0.12–0.92]) was significantly negatively associated with COVID-19 vaccine uptake.

Table 1.

Baseline sociodemographic characteristics and substance use behaviours associated with COVID-19 vaccine uptake among youth and young adults who use drugs in Vancouver, Canada from June to November 2021 (n = 301).

	COVID-19 Vaccination
Characteristic	Yes n (%) n = 151	No n (%) n = 150	Odds Ratio (95 % CI)	p - value
Age† (median, min & max)	28.4 (20.1–38.7)	29.7 (20–39.5)	0.95 (0.90–1.00)	0.062
Self-identified gender
Men	92 (60.9)	84 (56)
Women or other‡	59 (39.1)	66 (44)	1.23 (0.77–1.94)	0.386
Race/Ancestry
BIPOC	54 (35.8)	66 (44)
white	95 (62.9)	83 (55.3)	0.71 (0.45–1.14)	0.157
Homelessness*
yes	27 (17.9)	35 (23.3)
no	124 (82.1)	115 (76.7)	0.72 (0.41–1.25)	0.243
Employment*
yes	75 (49.7)	71 (47.3)
no	76 (50.3)	79 (52.7)	1.10 (0.70–1.73)	0.685
Suspected COVID-19
yes	31 (20.5)	22 (14.7)
no	118 (78.2)	119 (79.3)	1.42 (0.78–2.62)	0.253
Annual influenza/flu shot
yes	65 (43.1)	45 (30)
no	86 (57)	105 (70)	1.76 (1.10–2.85)	0.019
≥ Weekly injection*
yes	34 (22.5)	40 (26.7)
no	115 (76.2)	109 (72.7)	0.81 (0.47–1.36)	0.422
≥ Weekly cocaine use*
yes	5 (3.3)	11 (7.3)
no	144 (95.4)	138 (92)	0.44 (0.13–1.23)	0.132
≥ Weekly crack use*
yes	6 (4)	15 (10)
no	143 (94.7)	134 (89.3)	0.37 (0.13–0.95)	0.049
≥ Weekly heroin/fentanyl use*
yes	64 (42.4)	59 (39.3)
no	87 (57.6)	91 (60.7)	1.13 (0.72–1.80)	0.59
≥ Weekly methamphetamine use*
yes	61 (40.4)	64 (42.7)
No	90 (59.6)	86 (57.3)	0.91 (0.58–1.44)	0.69
≥ Weekly NMPO use*
yes	8 (5.3)	10 (6.7)
no	142 (94)	138 (92)	0.78 (0.29–2.03)	0.607
≥ Weekly cannabis use*
yes	78 (51.7)	91 (60.7)
no	73 (48.3)	59 (39.3)	0.69 (0.44–1.09)	0.116
≥ Weekly alcohol use*
yes	54 (35.8)	45 (30)
no	97 (64.2)	105 (70)	1.30 (0.80–2.11)	0.288
≥ Weekly tobacco use*
yes	109 (72.2)	112 (74.7)
no	42 (27.8)	38 (25.3)	0.88 (0.53–1.47)	0.626
Drug/alcohol treatment*
yes	84 (55.6)	45 (30)
no	64 (42.4)	103 (68.7)	3.00 (1.87–4.87)	<0.001
Receipt of prescribed safer supply*
yes	28 (18.5)	10 (6.7)
no	117 (77.5)	139 (92.7)	3.33 (1.60–7.46)	0.002
Non-fatal overdose*
yes	19 (12.6)	17 (11.3)
no	131 (86.8)	132 (88)	1.13 (0.56–2.28)	0.738
Safe injection/overdose prevention site use*
yes	32 (21.2)	25 (16.7)
no	118 (78.2)	125 (83.3)	1.36 (0.76–2.44)	0.304
Incarceration*
yes	13 (8.6)	12 (8 %)
no	136 (90.1)	138 (92)	1.10 (0.48–2.53)	0.821

^†Per one-year increase.

^‡Includes participants who identify as transgender, Two-Spirit and ‘other’.

^*Activities reported in last 6 months.

Table 2.

Multivariable analysis of factors associated with COVID-19 vaccine uptake among youth and young adults who use drugs in Vancouver, Canada from June to November 2021 (n = 301).

Variable	Adjusted Odds Ratio (AOR)	95 % Confidence Interval (CI)	p - value
Annual influenza/flu shot
(yes vs. no)	1.49	0.89–2.48	0.127
≥ Weekly crack use*
(yes vs. no)	0.35	0.12–0.92	0.042
Addiction Treatment*
(yes vs. no)	2.46	1.47–4.14	<0.001
Receipt of prescribed safer supply*
(yes vs. no)	2.33	1.03–5.62	0.048

^*Activities reported in last 6 months.

Of the 63 (20.9%) participants that reported receiving one dose of the COVID-19 vaccine, 52 (82.5%) reported they intended to get a second dose, 5 (7.9%) reported they do not intend to get a second dose, and 6 (9.5%) reported they were unsure. Unvaccinated participants were also asked if they intended to get vaccinated once a vaccine was available to them, and 51 (34%) reported ‘yes’, 69 (46%) reported ‘no’, and 30 (20%) responded ‘don’t know’. Among unvaccinated participants who indicated they would not get vaccinated if a vaccine was available to them (Table 3; n = 69), the top three reasons for vaccine hesitancy were safety concerns, specifically reporting being worried about long-term serious side effects (n = 29; 27.4%), not trusting government/doctors (n = 18; 17.0%), and not believing that COVID-19 is as serious as the government is claiming (e.g., it’s a conspiracy) (n = 9; 8.5%).

Table 3.

Reasons for COVID-19 vaccine hesitancy among unvaccinated youth and young adults who use drugs in Vancouver, Canada from June to November 2021 (n = 106 [unique respondents = 69]).

	n (%)
I don’t believe vaccines are safe (worried about long-term serious side effects)	29 (27.4)
I don’t trust the government or doctors	18 (17.0)
I don’t believe COVID-19 is as serious as government is saying (e.g. a hoax)	9 (8.5)
I don’t want to be in the first wave of people vaccinated	8 (7.5)
I don’t think I’m at risk for COVID-19	7 (6.6)
Acute side effects	5 (4.7)
Don’t like needles	5 (4.7)
Personal choice	5 (4.7)
I have already had COVID-19 (e.g. I think I’m immune)	3 (2.8)
Other	14 (13.2)
Don’t know	3 (2.8)
Refusal	1

Participants that did not report getting vaccinated were also asked if they would reconsider getting vaccinated under different scenarios. The results from these participants (n = 68; one participant refusal to respond to prompts and were excluded) are displayed in Table 4. If the vaccines were “used for an extended period of time with no major side effects or harms reported” 15 (21.7%) participants indicated that they would reconsider getting vaccinated. Eight (11.6%) participants reported that they would reconsider if they could choose which vaccine they would receive. If “COVID-19 deaths keep rising in BC” or if “multiple countries all use the same vaccine to prevent COVID-19 (not just Canada)”, 6 (8.7%) and 5 (7.3%) participants, respectively, indicated they would reconsider receiving a COVID-19 vaccine.

Table 4.

Scenarios for which youth and young adults who use drugs in Vancouver, Canada, would reconsider getting vaccinated against COVID-19 (June-November 2021) (n = 68).

	Yes n (%)	No n (%)	Don’t know n (%)
The vaccine is used for an extended period of time with no major side effects or harms reported	15 (21.7)	47 (68.1)	6 (8.7)
I could choose which vaccine I would receive (n = 661)	8 (11.6)	52 (75.4)	6 (8.7)
COVID-19 deaths keep rising in BC (n = 661)	6 (8.7)	54 (78.3)	6 (8.7)
Multiple countries all use the same vaccine to prevent COVID-19 (not just Canada) (n = 622)	5 (7.3)	56 (81.2)	6 (8.7)
COVID-19 infection continues or starts to spread widely in BC (n = 661)	(5.8)	56 (81.2)	6 (8.7)

^1.2 participants did not answer this question.

^2.6 participants did not answer this question.

4. DISCUSSION

In the present study among YWUD located in Vancouver, Canada, only half of the participants interviewed had received at least one dose of a COVID-19 vaccine between June and November 2021. In a multivariable analysis, engagement in addiction treatment and connection with prescribed safer supply initiatives were positively associated with COVID-19 vaccination, whereas weekly crack use was negatively associated with vaccination. The most frequently reported reason for vaccine hesitancy was safety concerns, specifically, concerns regarding the long-term side effects of the vaccines. Participants reported that their vaccine confidence would increase if the vaccine was used for an extended period of time with no side effects or if they could choose the type of vaccine they would receive.

Vaccine uptake among YWUD in our study was found to be significantly lower than the general population in the study setting during the same time period. As of June 3, 2021, 75% of people living in B.C., aged 18 plus had received the first dose of a COVID-19 vaccine and 7% received two doses [10].

As of November 29, 2021, 93% of people living in B.C., aged 18 plus, had received the first dose of a COVID-19 vaccine and 89% had received their second dose [10], compared to 50.2% and 28.9%, respectively, in this study (as of November 2021). Among younger people aged 18–29 years in the general population, 97% received their first vaccine dose and 91% received two doses [10]. For comparison among adults who use drugs in Vancouver during the same time period (June to November 2021), 74.5% (3 1 2) of 419 received at least one dose and 57% (2 3 9) reported receiving two vaccine doses (Vancouver Injection Drugs Users Study, unpublished data, 2023), compared to 50.2% and 28.9%, respectively, in the current study [28]. There are likely numerous factors contributing to the lower vaccination rate in our sample, including barriers to accessing health and social services such as experiences of stigma or discrimination, a lack of youth-specific services for YWUD, housing instability, high-intensity drug use, interactions with law enforcement, drug market activity, and histories of violence and physical abuse [29], [30]. To our knowledge, this is the first investigation of vaccine uptake among YWUD and further studies are needed to characterize vaccine uptake as additional doses are required to manage emerging variants.

Our finding that recent engagement in addiction treatment and engagement in prescribed safer supply initiatives were significantly associated with vaccine uptake suggests that increased health system engagement increased the higher likelihood of vaccination. Our findings align with a recent study conducted by Iversen et al. that surveyed adults who use injection drugs in Australia and found that participants who were currently receiving opioid agonist therapy (OAT) were more likely to be vaccinated against COVID-19 (2022). Among PWUD, an established connection to the healthcare system, specifically addiction treatment and harm reduction services, may facilitate trusting relationships with medical personnel and decrease barriers to accessing COVID-19 vaccines compared to those who are not connected to the healthcare system [31], [32]. Such contacts may also afford opportunities to provide accurate information about vaccines as well as opportunities to dispel related myths. The literature has well characterized the barriers to accessing healthcare that impacts PWUD, including stigma and discrimination [24], [33], [34]. These findings suggest that efforts to connect YWUD to the healthcare system and novel harm reduction interventions may be a helpful strategy to increase vaccine uptake.

We found that participants who were engaged in at least weekly crack use were less likely to be vaccinated against COVID-19. Crack use may be a proxy for higher-intensity substance use, specifically crack cocaine has a shorter half-life compared to opioids and consumption may occur more frequently as a result [35], [36], [37]. In the Australian study, adults who use drugs participants who were engaged in frequent injection drug use were significantly less likely to be vaccinated [18]. However, a study analyzing vaccine willingness in the San Diego-Tijuana border region did not find an independent association between substance use variables and vaccine hesitancy [22]. Prior research has characterized the positive association between high-intensity substance use and barriers to accessing health and social services [25], [29]. Specifically, YWUD experience unique barriers which can include, difficulty establishing trust with adults and authority figures, prior negative experiences with health and social services, and long waitlists for services [29]. These factors may explain, at least in part, the association between frequent crack use and vaccine hesitancy in the present study.

Our findings suggest that the rationale behind vaccine hesitancy in our sample centers primarily on safety concerns and a lack of trust in the government and the medical system. Prior research accessing vaccine willingness among adults who use drugs found that vaccine safety concerns are common [21], [22], [38], which is also consistent with the general population [39], [40], [41]. These findings suggest that broader strategies to combat misinformation, provide information related to the efficacy and safety of vaccines, and promote public health targeted to the general population could be tailored and targeted to meet the unique needs of this population. Many PWUD experience barriers to accessing healthcare, which stems from stigma, discrimination and criminalization, which can result in mistrust and healthcare avoidance, and may be influencing the lack of confidence in COVID-19 vaccines [33]. Information regarding vaccination safety may be better received if delivered by trusted sources, such as harm reduction services and peer-based organizations [22]. While this research cannot confirm whether the reduced rate of COVID-19 vaccination among YWUD in our sample is a result of experiences of stigma in healthcare acting as a barrier, previous research has highlighted the detrimental effect of stigma on PWUD’s overall health [24], [33], [34]. As such, interventions to reduce stigma in healthcare and greater outreach to meet PWUD in community settings may positively impact COVID-19 vaccination rates and overall health of this population.

There are several limitations associated with this study. As with all studies involving difficulty to reach population, study participants were not randomly selected. Findings may therefore not be generalizable to other YWUD in Vancouver, Canada and to other settings. ARYS is, however, believed to be reflective of high risk structurally marginalized young people who use drugs. Aligned with other samples of young people who use drugs, such as the ‘RAPIDS’ study in Rhode Island, rates of active homelessness are high (20.6% in ARYS and 18% in RAPIDS) and regular opioid use (40.9% ARYS and 37% RAPIDS) [42]. Despite uncertainty with respect to the exact representativeness of the sample, the documented discrepancy between vaccine uptake in our sample of structurally marginalized young people and the general population of young people, provides clear signals that public health pandemic response efforts had lower success among this unique population. Also, with respect to sample representativeness, it is possible that during the COVID-19 pandemic, participants who were more cautious about public health restrictions were less likely to attend a study visit. It is anticipated that participants included in this study were likely less concerned about COVID-19 generally. However, we took a number of steps to reduce possible influence of this selection bias, including contacting participants eligible for a study visit via social media, email, and phone, in addition to conducting remote interviewers and loaning participants mobile phones who did not have access to one to complete a study interview.

Since this is a cross-sectional study, it is not possible to make causal inferences and residual confounding may have influenced the associations we observed. The data collected was based on self-report which creates a risk of recall or social desirability bias; however, previous research on self-reporting substance use and stigmatized behaviours among PWUD has been shown to be valid and reliable when compared to objective measures [43]. Lastly, unvaccinated participants were asked a number of follow-up questions within the survey, including whether or not they intended to get vaccinated once a vaccine became available to them and participants who answered ‘no’ were asked further questions regarding the reasons for their vaccine hesitancy and if there were scenarios under which they would reconsider getting vaccinated. Only respondents who answered ‘no’ to the question regarding intent to get vaccinated (n = 69) were asked the proceeding questions regarding reasons for vaccine hesitancy and scenarios under which they would reconsider. Importantly, 30 (20%) respondents who responded that they ‘don’t know’ whether or not they would get vaccinated once a vaccine became available, were not asked these follow-up questions, which is a limitation to the interpretation of the data regarding vaccine hesitancy and scenarios in which a participant would reconsider getting vaccinated, suggesting that this data speaks more to vaccine hesitancy for those who do not intend to ever get vaccinated and does not speak to those who are indecisive about getting vaccinated.

In summary, among our sample of YWUD, only half of the participants had received at least one dose of a COVID-19 vaccine as of November 2021, which is notably lower than both the adult population of PWUD in Vancouver (74.5%) and the general population in BC (93%) at the time of reporting. Vaccine hesitancy was found to be primarily driven by safety concerns, which aligns with evidence from the general population and points to opportunities to tailor broad strategies to combat misinformation and promote public health to meet the unique needs and barriers experienced by this population. Participants who had accessed addiction treatment and prescribed safer supply initiatives were more likely to be vaccinated against COVID-19 and those who were engaged in high-intensity stimulant use were less likely to be vaccinated against COVID-19. Findings suggest that efforts to connect YWUD to the healthcare system and novel harm reduction interventions may also increase vaccine uptake.

HIGHLIGHTS.

• Data from the At-Risk Youth Study a prospective cohort in Vancouver, Canada.

• 50.2% of participants reported receipt of at least one dose of a SARS-CoV-2 vaccine.

• Outcome associated with addiction treatment and receipt of prescribed safer supply.

• Vaccine uptake was also negatively associated with weekly crack use.

• Connecting youth to healthcare and harm reduction interventions may increase uptake.

Data availability

The data that has been used is confidential.