The evolution of workplace risk for Covid-19 in Canadian healthcare workers and its relation to vaccination : a nested case-referent study

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DOI

https://doi.org/10.1002/ajim.23466

Language of the publication
English
Date
2023-02-03
Type
Article
Author(s)
  • Cherry, Nicola
  • Mhonde, Trish
  • Adisesh, Anil
  • Burstyn, Igor
  • Durand-Moreau, Quentin
  • Labrèche, France
  • Ruzycki, Shannon
Publisher
Wiley Periodicals LLC

Abstract

Background
During the early months of the Covid-19 pandemic, studies demonstrated that healthcare workers (HCWs) were at increased risk of infection. Few modifiable risks were identified. It is largely unknown how these evolved over time.

Methods
A prospective case-referent study was established and nested within a cohort study of Canadian HCWs. Cases of Covid-19, confirmed by polymerase chain reaction, were matched with up to four referents on job, province, gender, and date of first vaccination. Cases and referents completed a questionnaire reporting exposures and experiences in the 21 days before case date. Participants were recruited from October 2020 to March 2022. Workplace factors were examined by mixed-effects logistic regression allowing for competing exposures. A sensitivity analysis was limited to those for whom family/community transmission seemed unlikely.

Results
533 cases were matched with 1697 referents. Among unvaccinated HCWs, the risk of infection was increased if they worked hands-on with patients with Covid-19, on a ward designated for care of infected patients, or handled objects used by infected patients. Sensitivity analysis identified work in residential institutions and geriatric wards as high risk for unvaccinated HCWs. Later, with almost universal HCW vaccination, risk from working with infected patients was much reduced but cases were more likely than referents to report being unable to access an N95 mask or that decontaminated N95 masks were reused.

Conclusions
These results suggest that, after a rocky start, the risks of Covid-19 infection from work in health care are now largely contained in Canada but with need for continued vigilance.

Subject

  • Health,
  • Coronavirus diseases,
  • Workplace,
  • Health professionals

Rights

Pagination

297-306

Peer review

Yes

Open access level

Gold

Identifiers

PubMed ID
36734295
ISSN
1097-0274

Article

Journal title
American Journal of Industrial Medicine
Journal volume
66
Journal issue
4

Sponsors

Seed funding was obtained from the College of Physicians and Surgeons of Alberta. Grant funding was obtained from the Canadian Institutes of Health Research (Funding Reference number 173209). This funding was extended by a grant from the Canadian Immunology Task Force.

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Collection(s)

Communicable diseases

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