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Original research
Variation in occupational exposure risk for COVID-19 workers’ compensation claims across pandemic waves in Ontario
  1. Peter M Smith1,2,
  2. Qing Liao1,
  3. Faraz Shahidi1,2,
  4. Aviroop Biswas1,
  5. Lynda S Robson1,
  6. Victoria Landsman1,
  7. Cameron Mustard1
  1. 1 Institute for Work & Health, Toronto, Ontario, Canada
  2. 2 Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
  1. Correspondence to Dr Peter M Smith, Institute for Work and Health, Toronto, ON M5G 1S5, Canada; psmith{at}


Objectives To understand rates of work-related COVID-19 (WR-C19) infection by occupational exposures across waves of the COVID-19 pandemic in Ontario, Canada.

Methods We combined workers’ compensation claims for COVID-19 with data from Statistics Canada’s Labour Force Survey, to estimate rates of WR-C19 among workers spending the majority of their working time at the workplace between 1 April 2020 and 30 April 2022. Occupational exposures, imputed using a job exposure matrix, were whether the occupation was public facing, proximity to others at work, location of work and a summary measure of low, medium and high occupational exposure. Negative binomial regression models examined the relationship between occupational exposures and risk of WR-C19, adjusting for covariates.

Results Trends in rates of WR-C19 differed from overall COVID-19 cases among the working-aged population. All occupational exposures were associated with increased risk of WR-C19, with risk ratios for medium and high summary exposures being 1.30 (95% CI 1.09 to 1.55) and 2.46 (95% CI 2.10 to 2.88), respectively, in fully adjusted models. The magnitude of associations between occupational exposures and risk of WR-C19 differed across waves of the pandemic, being weakest for most exposures in period March 2021 to June 2021, and highest at the start of the pandemic and during the Omicron wave (December 2021 to April 2022).

Conclusions Occupational exposures were consistently associated with increased risk of WR-C19, although the magnitude of this relationship differed across pandemic waves in Ontario. Preparation for future pandemics should consider more accurate reporting of WR-C19 infections and the potential dynamic nature of occupational exposures.

  • COVID-19
  • Epidemiology
  • Public health

Data availability statement

Data may be obtained from a third party and are not publicly available.

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Data availability statement

Data may be obtained from a third party and are not publicly available.

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  • Contributors PMS, FS and CM developed the study idea. QL performed the analysis with assistance from VL, FS and PMS. All authors discussed interpretation of the study findings. PMS wrote the first draft of the manuscript. All authors provided substantive comments and suggestions. All authors have reviewed the final version of the manuscript and have approved it for submission. PS is guarantor for the paper.

  • Funding This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. All authors worked for the Institute for Work and Health while this project was completed. The Institute for Work and Health is supported through funding from the Ontario Ministry of Labour, Immigration, Training and Skills Development (MLITSD).

  • Disclaimer The analyses, conclusions, opinions and statements expressed herein are solely those of the authors and do not reflect those of the MLTSD; no endorsement is intended or should be inferred.

  • Competing interests PMS is an editor at Occupational and Environmental Medicine. He was not involved in any part of the peer-review process for this manuscript.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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