Determinants of post-COVID ill-health in a cohort of Canadian health care workers

  • Author / Creator
    Zadunayski, Tanis K
  • Abstract
    During the COVID-19 pandemic, health care workers (HCW) were at risk of SARS-CoV-2 infection and of developing a post-COVID condition (PCC). Post-COVID conditions are generally defined to occur following the onset of COVID-19, be present after 3 months, and persist for at least 2 months. The objectives of this study were to determine health complaints by HCW attributed to COVID-19, examine the prevalence of a post-COVID condition among HCW and attempt to identify pre-pandemic factors and factors associated with experiences during the pandemic that increase or decrease risk of post-COVID symptoms among HCW.
    A prospective cohort of Canadian HCW was recruited at the beginning of the pandemic in March 2020. Questionnaires were distributed online four times to those who consented, from the start of the pandemic to summer 2022. Questionnaires collected data on demographics, pre-pandemic medical history, COVID-19 infections, symptoms and severity, vaccination status, work-related factors, and mental health. The 2022 questionnaire additionally asked participants if they have had a condition they believed to be a result of, or made worse by, their COVID-19 infection. From the full cohort, we selected a sub-cohort that included all those with only one positive COVID-19 test who had completed the 2022 questionnaire. Test dates for Alberta, British Columbia and Quebec participants were validated with provincial health records. Within this sub-cohort, the proportion with a PCC was estimated for those with a case date at least 90 days before completion of the questionnaire. Binary logistic regression was used to evaluate the relationship between PCC and risk factors in a model allowing for gender, age, and HCW job type.
    The full cohort comprised 4964 HCW. In our sub-cohort (N=1653), 967 had a positive COVID-19 test at least 90 days before completing the questionnaire. Among these HCW, we estimated a post-COVID condition prevalence of 27%. (n=263). In our final model, a PCC was least likely to be reported by physicians and was not related to gender or age. The following factors increased the likelihood of a PCC in the multivariable model: higher pre-infection anxiety (OR=1.06, 95% CI: 1.02-1.10), a pre-existing mental health condition other than anxiety or depression (OR=4.55, 95% CI: 1.29-16.02), a pre-existing chronic condition other than respiratory or mental health (OR=1.90, 95% CI: 1.35- 2.67) and perception of being infected at work (OR= 1.52, 95% CI: 1.09-2.12). Number of vaccines received prior to infection reduced the likelihood of a PCC (OR=0.77, 95% CI: 0.66-0.89). When stratified by vaccination status, unvaccinated HCW infected later in the pandemic, compared to earlier, were less likely to develop a PCC (OR= 0.84, 95% CI: 0.74 to 0.95). Symptom severity from initial infection increased risk, specifically from chest pain (OR=1.49, 95% CI: 1.22-1.81), shortness of breath (OR=1.22, 95% CI: 1.04-1.44) and trouble thinking (OR=1.75, 95% CI: 1.45-2.11). HCWs rated functional limitation due to a PCC at a median of 31% and 27% for classic and non-classic symptoms respectively, and 98% of all HCW working at the time of their infection returned to work in 30 days or less. A severe PCC (n=57) was more likely among nurses and those with higher pre-infection anxiety and was reduced as number of vaccines increased.
    Certain pre-existing factors and factors experienced during the pandemic predisposed HCW to a PCC. Overall, HCWs generally did not report a severe PCC, with almost all HCW returning to work quickly after infection. As HCW continue to face potential new waves and increased risk of infection and of developing a post-COVID condition, it is important to identify vulnerable groups and modifiable factors to help mitigate the deleterious long-term effects, both at a personal and occupational level.

  • Subjects / Keywords
  • Graduation date
    Spring 2024
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.