Incidence of severe COVID-19 among 1.2 million workers in Ontario, Canada

Sritharan J, Song C, Harris MA, Kirkham TL, Smith BT, Kim J, Arrandale VH, Demers PA. Incidence of severe COVID-19 among 1.2 million workers in Ontario, Canada. Occupational Medicine. Published online May 5, 2025:kqaf017. doi:10.1093/occmed/kqaf017

Background: The disproportionate impact of coronavirus disease (COVID-19) on healthcare workers has been highlighted; however, there is a lack of evidence regarding other high-risk occupations and industries.

Aims: This study estimated the risk of severe COVID-19 among a large cohort of workers in Ontario, Canada.

Methods: This study used a cohort of 1.2 million workers identified using workers’ compensation claims records (1983-2019). Identified workers were linked with emergency department (ED) visits and hospitalizations (2020-2021). Cases coded as U0.71 (virus detected, confirmed case) were identified from ED visits and hospitalizations. Hazard ratios (HRs) and 95% confidence intervals (CI_95%) for COVID-19 for each occupational group compared to all other workers in the cohort were calculated, adjusting for age and birth year. Standardized incidence ratios and 95% CI, comparing workers to the general population of Ontario were also calculated, adjusting for age, sex, year and region.

Results: A total of 10 322 severe COVID-19 cases among workers were identified through ED visits and hospitalizations. Workers in material handling (HR=1.32, CI_95%=1.21–1.43), medicine and health (HR=1.27, CI_95%=1.18–1.37), processing (food, water, textile) (HR=1.23, CI_95%=1.12–1.36) and machining occupations (HR=1.11, CI_95%=1.02–1.20) had some of the highest risks of COVID-19 when compared to all other workers in the cohort. Findings were somewhat consistent when comparing workers to the general population of Ontario.

Conclusions: Certain groups of workers in this cohort demonstrated elevated risks of severe COVID-19. The findings align with previous studies and emphasize the need to include occupational surveillance methods in future pandemic preparedness in Canada.