The impact of COVID-19 vaccine distribution channels on equity-deserving populations: a Canadian population-based cohort study using administrative data

Uptake of COVID-19 vaccines among equity-deserving populations was a challenge throughout the Canadian vaccination campaign. This necessitated the implementation of vaccine distribution strategies that targeted specific populations. As a result, different vaccine channels were introduced in each province. The purpose of this study is to examine the effect of COVID-19 vaccine distribution channels on short-term vaccination rates amongst equity-deserving populations. Retrospective, population-based cohort using linked administrative claims data based in the Canadian provinces of Manitoba, Ontario, and Newfoundland and Labrador. The study population included all residents, 12 years and older, who were living in one of the three provinces with at least 1 day of health coverage between Jan 1, 2021, and Dec 31, 2021. The index event was receiving one COVID-19 vaccination. Difference-in-differences analyses were used to evaluate the impact of various COVID-19 vaccine distribution channels, such as directed at-risk, mass vaccination clinics, pharmacies, primary care offices, and long-term care facilities, on the gap in vaccination coverage between select equity-deserving and non-equity deserving populations. The equity-deserving populations included having lower household income, identifying as a visible minority, being a recent immigrant, and being an adult without a high school diploma. The total COVID-19-vaccinated population as of December 31, 2021 was 998,906 (85% of total population) in Manitoba, 10,866,548 (89% of total population) in Ontario, and 485,901 (99% of total population) in Newfoundland and Labrador. The analyses were limited by significant data challenges; data on where (which channel) specific individuals received their vaccination were limited. Though findings were mixed, in general, the COVID-19 vaccine coverage one month after the initiation of a new vaccine distribution channel increased less for the equity deserving groups than those of the general population. An increase in the observed equity gaps immediately after new vaccine channel introductions may be explained by new channels providing vaccines at a lower volume than mass-vaccination clinics or may reflect limitations in the data infrastructure. The collection of uniform data across Canada should be prioritized to facilitate comprehensive evaluation of the health system response to future pandemics, including the ability to monitor the impact of the response on population inequities.