COVID-19 Vaccination among People Affected by Sexually Transmitted and Bloodborne Infections, Methamphetamine Use and their Intersection in Manitoba, Canada: A Retrospective Matched Cohort Analysis Using Population-Based Administrative Healthcare Data (2020-2022)

Objectives

To examine COVID-19 vaccine uptake among people diagnosed with sexually transmitted and bloodborne infections (STBBI), people with healthcare-documented methamphetamine use, and those experiencing both exposures in Manitoba, Canada.

Methods

We conducted a retrospective matched-cohort study using linked population-based administrative healthcare, laboratory, and vaccination databases in Manitoba. Individuals aged ≥16 years with laboratory-confirmed chlamydia/gonorrhea (CT/NG), syphilis, HIV, and/or documented methamphetamine use during the four years prior to March 1, 2020 were included in eight exposed cohorts. Each cohort was matched to unexposed comparators on age, sex, geographic region, and income quintile. The primary outcome was receipt of ≥2 COVID-19 vaccine doses between December 1, 2020 and March 31, 2022. Poisson regression models estimated adjusted rate ratios (aRRs) and 95% confidence intervals (95% CIs) for vaccine uptake.

Results

Compared with matched comparators, most exposed cohorts were less likely to complete the COVID-19 primary vaccine series. Individuals in the Syphilis Only (aRR: 0.83, 95% CI: 0.80–0.86), Syphilis Plus (aRR: 0.77, 95% CI: 0.74–0.79), CT/NG Only (aRR: 0.91, 95% CI: 0.90–0.92), CT/NG Plus (aRR: 0.74, 95% CI: 0.72–0.77), Methamphetamine Only (aRR: 0.71, 95% CI: 0.68–0.73), and Methamphetamine + STBBI cohorts (aRR: 0.64, 95% CI: 0.62–0.67) had significantly lower vaccine uptake. The HIV Only cohort did not differ significantly from matched comparators (aRR: 0.97, 95% CI: 0.93–1.004). Lower uptake was concentrated among individuals living in lower-income areas.

Conclusions

Populations affected by STBBI, reported methamphetamine use, or both experienced significant inequities in COVID-19 vaccine uptake, particularly those with multiple STBBIs and concurrent substance use. Integrated vaccination approaches linked with HIV, harm reduction, and addiction services may improve vaccine equity during future public health emergencies.

STRENGTHS AND LIMITATIONS OF THIS STUDY

• Population-based study using objective measures of COVID-19 vaccination.

• Regression models addressed confounding by age, geographic area, area-level income, healthcare utilization, and previous mental health and alcohol use disorder diagnoses.

• Does not capture individuals not interacting with healthcare system.

• Residual confounding can still be present, with no information on behavioural risk factors for STBBI, race/ethnicity, and individual-level socioeconomic measures.