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We couldn’t do it without you.

Thanks for being part of the Ontario Health Study (OHS). More than 60 promising research projects are already underway using the data you’ve provided — and there are many more to come. That’s why it’s important for you to stay involved! By completing our follow-up questionnaires, you’ll help give researchers across Canada even more data to work with to improve how cancer and chronic disease are detected and treated.

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Current Activities

In 2024, the OHS will be seeking a second blood sample from some of the 41,000 OHS participants who provided their first blood sample between 2009 and 2017. Collecting up to 3,000 second blood samples will mean the Study can offer researchers the opportunity to explore various changes to elements within the blood over time. Investigating these ‘biomarkers,’ especially in people who have not been diagnosed with a major disease, could help researchers develop better diagnostic screening tools, or explore the mechanisms of healthy aging. Read more.

Genotyping DNA samples is expected to wrap up in early 2024. Almost 12,000 additional samples will have been genotyped, bringing the total to more than 20,000. This will provide a large enough sample size for researchers to look for meaningful differences in how our genes are expressed.

Ongoing Activities

By January of 2023, nearly 10,000 OHS participants had provided up to three blood spot samples which were then analyzed for COVID-19 antibodies. Data from two of these three timepoints are now available to researchers.

Here’s a snapshot of data collected, between February 2021 to January 2023, for the COVID-19 Antibody Study:

22,120 CanPath participants, including 9,848 from the OHS (46%)

43% reported receiving two or fewer vaccine doses and 57% reported receiving three or more vaccine doses (data collected February 2021- January 2023).

Of the nearly 10,000 that provided bloodspot samples:

  • 42.3% received Pfizer-BioNTech
  • 10.3% received Moderna
  • 4.1% received Oxford-AstraZeneca
  • 28.1% received a combination of mRNA vaccines
  • 15.1% received a combination of viral vector (Astra-Zeneca) and mRNA (Pfizer, Moderna) vaccines

35% had a SARS-CoV-2 infection. Of that group, 90% had antibodies against the nucleocapsid protein of the virus, signaling a prior infection

The OHS and CanPath COVID-19 Antibody Study was designed by Dr. Philip Awadalla and Kimberly Skead with Dr. Victoria Kirsh from the OHS, and Dr. Philippe Broët of CARTaGENE. Funding to conduct this Study has been provided by the Government of Canada, through Canada’s COVID-19 Immunity Task Force, and by the Canadian Institutes of Health Research.

OHS Dataset

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Online questionnaires submitted by more than 224,000 participant volunteers across Ontario

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Unique data points available*

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MRIs collected

By continuing to take part in the OHS, you’ll be helping to find new ways to prevent and treat major diseases like cancer, heart disease and diabetes. You’ll also help to improve the health of future generations.

*These 1,600+ data points are common to other population health studies in Canada and around the world, allowing researchers to accurately compare results between studies and explore more challenging research questions.

OHS Biobank

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Blood samples collected


DNA samples genotyped

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Physical measurements

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Urine samples collected

Follow-up Questionnaires

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By remaining involved in the OHS, you will be invited to complete periodic follow-up questionnaires which will track how your health changes over time. These questionnaires will also ask about your exposures to different chronic disease risk factors.