This is a summary, written by members of the CITF Secretariat, of:

Xia Y, Ma H, Moloney G, García HAV, Sirski M, Janjua NZ, Vickers D, Williamson T, Katz A, Yiu K, Kustra R, Buckeridge DL, Brisson M, Baral SD, Mishra S, Maheu-Giroux M. Geographic concentration of SARS-CoV-2 cases by social determinants of health in metropolitan areas in Canada: a cross-sectional study. CMAJ 2022 February 14;194:E195-204. doi: 10.1503/cmaj.211249.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

In a study published in CMAJ by first author Yiqing Xia, a doctoral candidate, and CITF experts Drs. David Buckeridge and Mathieu Maheu-Giroux from McGill University, and Sharmistha Mishra from the University of Toronto used COVID-19 surveillance data from Jan 23, 2020, to Feb 28, 2021 to identify relevant social determinants of health – those factors influencing health outcomes that go beyond the strictly medical in metropolitan centres in Canada. Across all cities included in the study, COVID-19 cases were disproportionately concentrated in areas with lower income, a higher proportion of people living in high-density housing, lower levels of education, higher proportions of visible minorities, more recent immigrants, and higher concentrations of those deemed essential workers during the pandemic. The insights provided by this research can enable better allocation of resources, tailoring of policies and implementation of context-specific strategies to curb local transmission more effectively and efficiently.

The study included data from 16 cities from British Columbia, Manitoba, Ontario, and Quebec, accounting for 81% of COVID-19 cases in Canada. The focus was on transmission dynamics within the community.

Key Findings

  • Higher rates of infection were often correlated with:
    1. Lower income (defined differently according to province)
    2. Being an essential service worker (not amenable to remote working)
    3. Having lower education.

Lower education was also associated with barriers in access to health information and health care.

  • High-density households (more than 2 persons per bedroom) represented a barrier to physical distancing and effective isolation or quarantine. Importantly, this factor often correlated with lower income and education, and working in an essential service.
  • The rates of COVID-19 were higher among racialized communities or neighbourhoods with greater diversity. This has been a consistent finding across many countries, and reflects the outcome of systemic racism, including occupational exposure risks and barriers to prevention and access to effective isolation.

The researchers conclude that identifying city-specific patterns correlating COVID-19 cases with inequalities may be used to guide local responses to outbreaks of infection. It could lead to the more equitable allocation of resources and better access to interventions by providing services that meet the needs of communities at disproportionate risk. Such an approach may become even more important in the context of appropriately addressing the needs of disproportionately unvaccinated populations. Geographically prioritized allocation of resources and services that are tailored to the local drivers of inequalities in the risks of acquisition and transmission of COVID-19 offer a path forward in the public health response.