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  Conference on Retroviruses
and Opportunistic Infections
Seattle, Washington
Feb 19-22 2023
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Intervention efficacy on COVID-19 testing and vaccination in people who inject drugs
  Syringe Service Program Boosts Chances of COVID Testing in Drug Injectors
30th CROI, Conference on Retroviruses and Opportunistic Infections, February 19-22, 2023, Seattle
Mark Mascolini
A mobile syringe service program in San Diego independently raised chances of persuading people who inject drugs to get a COVID test when compared with standard teaching videos [1]. For still-uncertain reasons, the program proved more effective in homeless drug users than in those with housing.
People who inject drugs run a high risk of SARS-CoV-2 infection and severe COVID, but they have low testing and vaccination rates. In the San Diego-Tijuana La Frontera cohort, reported University of California, San Diego (UCSD) researchers who conducted this study, SARS-CoV-2 prevalence stood at 37% in 2021. Half of the group reported missing one or more recent opportunities to get a COVID test. In March 2022, fewer than 38% of cohort members in San Diego had one or more COVID vaccines.
Little knowledge about COVID testing and prevention, poor understanding of risks, distrust of institutions, and social and structural barriers to healthcare access all contribute to low COVID testing and vaccination rates in drug injectors, the UCSD team noted. But people who inject drugs often place more trust in syringe service programs, where they feel respected by a staff that often includes community peers. UCSD researchers took advantage of that trust in formulating a COVID testing outreach program for drug injectors.
From March through June 2022 via street outreach, the LinkUp program recruited drug injectors who were San Diego residents at least 18 years old, who had no recent voluntary COVID testing, and who had not been fully vaccinated against SARS-CoV-2. People willing to participate got $20. Interviewers administered baseline surveys outdoors in English or Spanish.
On different weeks trained peer counselors at mobile syringe service programs offered one of two interventions:
The Active LinkUp program consisted of (1) individually tailored COVID testing and vaccine education informed by Social Cognitive Theory and formative research and (2) motivational interviewing, problem solving, and planning.
A Didactic attention control program consisted of educational videos on COVID and cardiopulmonary resuscitation.
Each intervention lasted about 30 minutes, and after each intervention peer counselors offered rapid COVID antigen testing on site and vaccination referrals.
The LinkUp and Didactic programs both enrolled 75 participants, with similar proportions assigned male sex at birth (68.0% and 61.3%). Median ages were 38.0 in the LinkUp group and 45.0 in didactic controls. About one third of the LinkUp and didactic controls groups were Hispanic or Mexican, 81.3% and 65.3% were homeless, 17.6% and 9.3% were incarcerated in the past 6 months, 72.0% and 57.3% reported food insecurity since the COVID pandemic began, 21.6% and 22.7% were partially vaccinated against COVID, and 44.0% and 45.3% had prior mandatory COVID testing.
Preliminary vaccine outcomes favored the LinkUp program over the control program: 32% versus 13% accepted vaccine referrals (n = 150, P = 0.006), and 26% versus 17% had a new vaccine dose after the intervention (n = 110).
Overall, 92.0% in the LinkUp program and 62.7% of controls got tested for COVID after the intervention, a significant difference (P < 0.001). Testing detected only 1 SARS-CoV-2 infection. A multivariable model determined that the LinkUp group had a 20% greater likelihood of COVID testing after the intervention than the control group, independent of other variables (adjusted risk ratio [aRR] 1.20, 95% confidence interval [CI] 1.01 to 1.43). This analysis also determined that LinkUp increased the likelihood of COVID testing more in people homeless in the last 6 months (aRR 1.80, 95% CI 1.56 to 2.09) than in people not homeless (aRR 1.20, 95% CI 1.01 to 1.43).
The researchers could only speculate why LinkUp appeared to encourage COVID testing even more in homeless people than in people who were not homeless. Perhaps, they surmised, LinkUp had a particularly strong impact on homeless people because it restored trust in a vulnerable population with very little trust in health providers.
Overall, the UCSD investigators concluded that LinkUp increased COVID testing uptake and acceptance of vaccine referrals among drug injectors through mobile syringe service program sites in San Diego. They cautioned that the study was limited by use of a nonrandom participant sample recruited in "street sweeps." They also noted that some participant data depended on self-report and recall.
1. Bazzi AR, Abramovitz D, Harvey-Vera A, et al. Intervention efficacy on COVID-19 testing and vaccination in people who inject drugs. 30th CROI, Conference on Retroviruses and Opportunistic Infections, February 19-22, 2023, Seattle. Abstract 212.