This is a summary, written by members of the CITF Secretariat, of:

Coleman BL, Langley JM, McNeil S, Valiquette L, Vanderkooi O, Harrison R, Mubareka S, Muller M, Katz K, Loeb M, Powis J, Cooper C, Arnoldo S, Nadarajah J, Smieja M, Gingras A-C, Bennett S, Policelli J, Bowdish D, McGeer A. Risk factors for contracting COVID-19 in Canadian healthcare personnel, prior to and during the omicron wave. Poster at OPTIONS XI, September 26-29, 2022.

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

The Omicron wave caused a much higher number of SARS-CoV-2 infections in healthcare personnel than previous waves of pandemic activity. Group activities and working in close proximity with other people also increased the risk of SARS-CoV-2 infection. These interim results, which were not peer reviewed, were the subject of a poster presentation at the OPTIONS XI Congress by CITF-funded researchers Drs. Allison McGeer and Brenda Coleman (University of Toronto). This was a test-negative prospective cohort study that enrolled individuals aged 18-75 years old working in a healthcare setting for 20 hours or more per week. The enrollment period was from June 2020 to July 2022, involving 19 hospitals in nine Canadian cities.

Key Points:

  • During the Omicron wave (December 1, 2021 to August 1, 2022), there were 188.8 cases per 100,000 participant-days (850 cases/450,109) among healthcare workers. In contrast, prior to Omicron (January 1, 2020 to November 30, 2021), there were 5.6 cases per 100,000 participant-days (92 cases/1,632,585).
  • Workers who were exposed to household members known to be infected with SARS-CoV-2 were at particular risk of infection.
  • Group activities (those involving groups of 3 to 4 people posed the highest risk) and working in close proximity with other people (an office setting with co-workers or clients had the highest risk) were risk factors during the Omicron wave.