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

J Sritharan; C Song; M A Harris; T L Kirkham; B T Smith; J Kim; V H Arrandale; P A Demers

doi:10.1093/occmed/kqaf017

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

Occup Med (Lond). 2025 May 5:kqaf017. doi: 10.1093/occmed/kqaf017. Online ahead of print.

Authors

J Sritharan^{1

2}, C Song¹, M A Harris^{1

2

3}, T L Kirkham^{1

2}, B T Smith^{2

4}, J Kim^{2

5

6}, V H Arrandale², P A Demers^{1

2}

Affiliations

¹ Occupational Cancer Research Centre, Ontario Health, Toronto, Ontario M5G 2L3, Canada.
² Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario M5T 3M7, Canada.
³ School of Occupational and Public Health, Toronto Metropolitan University, Toronto, Ontario M5B 2K3, Canada.
⁴ Health Promotion, Chronic Disease and Injury Prevention, Public Health Ontario, Toronto, Ontario M5G 1M1, Canada.
⁵ Environmental and Occupational Health, Public Health Ontario, Toronto, Ontario M5G 1M1, Canada.
⁶ Department of Medicine, University of Toronto, Toronto, Ontario M5S 3H2, Canada.

PMID: 40325885
DOI: 10.1093/occmed/kqaf017

Abstract

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 (CI95%) 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, CI95%=1.21-1.43), medicine and health (HR=1.27, CI95%=1.18-1.37), processing (food, water, textile) (HR=1.23, CI95%=1.12-1.36) and machining occupations (HR=1.11, CI95%=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.

Abstract

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