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 (STBBIs), people with healthcare-documented methamphetamine use and those experiencing both exposures in Manitoba, Canada. DESIGN: Population-based retrospective matched cohort study using linked administrative healthcare, laboratory and vaccination data. SETTING: Manitoba, Canada, from 1 March 2020 to 31 March 2022. PARTICIPANTS: Manitoba residents aged ≥16 years with laboratory-confirmed chlamydia or gonorrhoea, syphilis or HIV and/or healthcare-documented methamphetamine use during the 4 years before 1 March 2020 were classified into eight mutually exclusive exposure cohorts. Individuals were matched with comparators without the corresponding exposure based on age, sex, geographical region and area-level income quintile. PRIMARY OUTCOME MEASURE: Receipt of ≥2 COVID-19 vaccine doses. Poisson regression models incorporating person-time were used to estimate adjusted rate ratios (aRRs) and 95% CIs. RESULTS: Compared with matched comparators, vaccine uptake was lower in the Syphilis Only (aRR 0.83, 95% CI 0.80 to 0.86), Syphilis Plus (aRR 0.77, 95% CI 0.74 to 0.79), Chlamydia/Gonorrhoea Only (aRR 0.91, 95% CI 0.90 to 0.92), Chlamydia/Gonorrhoea Plus (aRR 0.74, 95% CI 0.72 to 0.77), Methamphetamine Only (aRR 0.71, 95% CI 0.68 to 0.73) and Methamphetamine plus STBBI cohorts (aRR 0.64, 95% CI 0.62 to 0.67). Uptake in the HIV Only cohort was similar to that among matched comparators (aRR 0.97, 95% CI 0.93 to 1.00). Lower uptake was concentrated among individuals living in lower-income areas. CONCLUSIONS: COVID-19 vaccine uptake was lower among several populations affected by STBBIs, methamphetamine use or both, with the greatest disparity among people experiencing intersecting STBBI and methamphetamine-related exposures. Integrating vaccination with HIV, STBBI, harm-reduction and addiction services may improve vaccine equity during future public health emergencies.