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

Objectives: To examine COVID19 vaccine uptake among people diagnosed with sexually transmitted and bloodborne infections (STBBI) and reported methamphetamine users in Manitoba, Canada, during the acute phase of the COVID19 pandemic. 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+ COVID19 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 COVID19 primary vaccine series. Individuals in the Syphilis Only (aRR: 0.87, 95% CI: 0.85 0.90), Syphilis Plus (aRR: 0.84, 95% CI: 0.81 0.86), CT/NG Only (aRR: 0.95, 95% CI: 0.94 0.96), CT/NG Plus (aRR: 0.82, 95% CI: 0.80 0.85), Methamphetamine Only (aRR: 0.78, 95% CI: 0.76 0.80), and Methamphetamine + STBBI cohorts (aRR: 0.74, 95% CI: 0.72 0.77) had significantly lower vaccine uptake. The HIV Only cohort did not differ significantly from matched comparators (aRR: 0.98, 95% CI: 0.95 1.01). Lower uptake was concentrated among individuals living in lower-income areas. Conclusions: People diagnosed with STBBI and methamphetamine users in Manitoba experienced significant inequities in COVID19 vaccine uptake, particularly those with STBBI coinfections and concurrent substance use. Integrated vaccination approaches linked with HIV, harm reduction, and addiction services may improve vaccine equity during future public health emergencies.