Cohort of Canadian healthcare workers during the COVID-19 pandemic profiled

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

In this cohort profile published in BMJ Open, a CITF-funded study reported on the establishment of a longitudinal cohort of health care workers (HCWs) employed in hospitals, residential institutions, and the community. Researchers used the cohort to examine factors in the workplace that might serve to mitigate risk of either SARS-CoV-2 infection or mental distress related to work demands, availability of personal protective equipment, vaccination, and infection during the pandemic. This study was led by Dr. Nicola Cherry (University of Alberta).

Participants were recruited in March 2020 from Alberta, British Columbia, Ontario, and Quebec. The cohort includes physicians (MDs), registered nurses (RNs), licensed practical nurses (LPNs), personal support workers (PSWs), and healthcare aides (HCAs). Blood samples were taken for serology testing before and after vaccination. Measurements of anxiety, depression, and sources of stress were conducted throughout the course of the pandemic.

Key findings:

• At baseline, the cohort included 29% MDs, 63% RNs, 1.4% LPNs, 4.7% PSWs, and 1.6% HCAs. The majority were aged 40 years and older (62%), with a higher proportion of PSWs (76%) and HCAs (73%) being over 40. Overall, 83% were women, 83% self-identified as white, 88% were in direct contact with patients in person or virtually, and 24% reported having been treated for anxiety or depression in the 12 months before the pandemic.
• By the fourth questionnaire in Spring 2022, many participants were retained, with a response rate of 89%.
• 92% of participants received at least one vaccine dose and 60% gave post-vaccine blood samples. Ease of accessing blood collection sites was a strong determinant of participation in the serology sub-cohort.
• In the early phase of the pandemic, unvaccinated HCWs were at greater risk of infection if they worked hands-on with patients on a ward designated for care of COVID-19 patients, or handled objects used by infected patients.

The serology results and demographic data from this study will be added to the CITF Databank. Linkage of study results with provincial administrative health databases will permit case validation, investigation of longer-term sequelae of infection, and comparison with community controls.

Participants were asked to complete questionnaires at four study phases: Spring 2020, Fall 2020, Spring 2021, and Spring 2022. Pre-vaccine blood samples were taken in October 2020, and post-vaccine blood samples were taken between March 2021 and July 2022. A study to compare infected (with a positive PCR test) vs. uninfected HCWs after their first vaccine dose was established within the cohort between October 2020 and March 2022.