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COVID-19 studies for hospital and healthcare staff (CCS & CCCS)

Status: Enrolment complete, thank you Study Results French site

What is the purpose of the study?

The COVID-19 Cohort Study (CCS) and the Canadian CCS (CCCS) are following staff to December 2023 to find out the rate of COVID-19 infection, antibody levels over time, the impact of vaccines against COVID-19, and the psychological impact of working during a pandemic.

How long will the study last?
The study will last until December 2023.

Who was asked to participate:
People working in an acute care, rehabilitation, or complex care hospital who:

  • were 18 to 75 years old
  • worked anywhere in the hospital for at least 20 hours per week
    • OR was a MD/NP with privileges who spends 8 hours or more per week in the hospital
  • was available for at least 3 months (not retiring or going on leave), and
  • had convenient access to a computer or a cell phone with internet access (to complete surveys and receive information about the study)

What did they need to do?

  1. An online survey at enrolment to assess current risk factors
  2. Short online surveys every week about whether they had any symptoms
  3. When tested for COVID-19: complete an illness report to inform the study of test results, symptoms, and contact with people who may have been ill
  4. Self-collect blood samples: 30 days after vaccination, 30 days after testing positive for COVID-19, and every 6 months after the more recent of these two. NOTE: The results are shared with participants, but it takes up to 6 months for results to be returned
  5. For Toronto-area sites: others in the household could consent to participate

Voluntary participation

Participants were provided with a small token of appreciation for taking part in the study

Thank you to our funders: CIHR: Canadian Institutes of Health Research, Weston Foundation, Physicians’ Services Inc., & COVID-19 Immunity Task Force



  Participating sites Investigators
Toronto  & area Oak Valley Health Dr. Jeya Nadarajah
Michael Garron Dr. Jeff Powis & Dr. Chris Kandel
North York General Dr. Kevin Katz
Private MD, NP, or midwifery clinics/practices in the GTA Dr. Brenda Coleman
Sinai Health Dr. Allison McGeer & Dr. Brenda Coleman
Sunnybrook Health Sciences Centre Dr. Samira Mubareka
Unity Health (St. Michael’s site) Dr. Matthew Muller
University Health Network Dr. Allison McGeer
William Osler Health System Dr. Saranya Arnoldo
Hamilton Hamilton Health Sciences Dr. Mark Loeb
St. Joseph’s Healthcare Hamilton Dr. Marek Smieja
Ottawa Ottawa Dr. Curtis Cooper
Calgary Calgary Health Zone Dr. Robyn Harrison
Edmonton Grey Nuns Community Hospital (Edmonton) Dr. Robyn Harrison
University of Alberta Hospital Dr. Robyn Harrison
Royal Alexandra Hospital Dr. Robyn Harrison
Nova Scotia
  IWK Health Dr. Joanne Langley
Nova Scotia Health Dr. Shelly McNeil
  Sherbrooke Dr. Louis Valiquette