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

Abstract

Background People who inject drugs (PWID) have low rates of COVID-19 testing yet are vulnerable to severe disease. In partnership with a mobile syringe service program (SSP) in San Diego County, CA, we developed the evidence-, community-, and Social Cognitive Theory-informed “LinkUP” intervention (tailored education, motivational interviewing, problem-solving, and planning) to increase COVID-19 testing uptake among PWID. Purpose To assess preliminary efficacy of LinkUP in increasing PWID COVID-19 testing in a pilot randomized controlled trial (RCT). Methods We referred participants (PWID, ≥18 years old, San Diego County residents who had not recently undergone voluntary COVID-19 testing) to mobile SSP sites that had been randomized (by week) to offer the active LinkUP intervention or didactic attention-control conditions delivered by trained peer counselors. Following either condition, counselors offered on-site rapid COVID-19 antigen testing. Analyses estimated preliminary intervention efficacy and explored potential moderation. Results Among 150 participants, median age was 40.5 years, 33.3% identified as Hispanic/Latinx, 64.7% were male, 73.3% were experiencing homelessness, and 44.7% had prior mandatory COVID-19 testing. The LinkUP intervention was significantly associated with higher COVID-19 testing uptake (p < .0001). Homelessness moderated intervention effects; LinkUP increased COVID-19 testing uptake more among participants experiencing homelessness (adjusted risk ratio [aRR]: 1.80; 95% CI: 1.56–2.09; p < .0001) than those not experiencing homelessness (aRR: 1.20; 95% CI: 1.01–1.43; p = .04). Conclusions Findings from this pilot RCT support the preliminary efficacy of the “LinkUP” intervention to increase COVID-19 testing among PWID and underscore the importance of academic-community partnerships and prevention service delivery through SSPs and other community-based organizations serving vulnerable populations.

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

“…Comparison of the 149 participants by condition at enrollment revealed that the 2 study arms were balanced with respect to proportions who were partially vaccinated against COVID-19 and other behavioral characteristics [ 10 ]. However, LinkUP intervention participants were significantly more likely to be younger and to have recently experienced homelessness or food insecurity ( Supplementary Table 1 ).…”

“…We relied on self-report of vaccine uptake behaviors, which may have elicited socially desirable responses. The limited size and scope of this trial preclude further exploration of potential mediators and moderators of intervention effects identified by theory, literature, or our team's previous research (eg, homelessness, which moderated LinkUP effects on the uptake of COVID-19 testing) [ 10 ]. It is possible that during the 6-month follow-up, participants could have received other interventions that influenced their decisions to become vaccinated.…”

“…All others were included in an intent-to-treat analysis ( Figure 1 ). Following CONSORT guidelines, we compared participant characteristics between the study conditions at enrollment ( Supplementary Table 1 ) [ 10 ] and between those who were interviewed at follow-up and those who were lost to follow-up. We used frequency, percentage, and chi-square or Fisher exact test for binary variables and median, IQR, and Mann-Whitney U test for continuous variables.…”

“…We accounted for potential clustering by specifying an exchangeable correlation structure for participants recruited during the same week. Possible covariates were selected from previous research with the same sample [ 6 , 10 , 21 ] and modified disjunctive cause criteria [ 21 ]. Variables yielding P values ≤.10 in univariate regressions were considered in multivariable models and retained when P ≤ .10.…”

“…As part of the RADx-UP initiative to increase uptake of COVID-19 testing and vaccination among marginalized US populations, we designed LinkUP, a brief social cognitive theory–based intervention with motivational interviewing (MI) delivered by trained counselors at SSP sites. In a randomized controlled trial [ 9 ], PWID randomized to LinkUP were significantly more likely to agree to rapid COVID-19 testing immediately following their counseling session, which was the primary outcome [ 10 ]. Herein, we evaluated the extent to which the LinkUP intervention was associated with the secondary outcomes of greater acceptance of COVID-19 vaccination referrals and subsequent COVID-19 vaccine uptake relative to the didactic attention-matched control condition.…”