Serosurveillance is an application of serology testing , which is a test performed on blood to detect the presence of antibodies. Serosurveillance is a common public health surveillance method.
PHO is conducting serosurveillance to better understand what proportion of the Ontario population has COVID-19 antibodies and to identify hotspots and high risk groups. This will enable the public health system and the government to evaluate the effectiveness of the pandemic response thus far, and take targeted steps to prevent further spread of COVID-19. Also, when a vaccine becomes available, serosurveillance can help determine priority groups for vaccination and help monitor the effectiveness of vaccination programs.
The testing is being done using blood from specimens submitted for other tests performed at PHO’s laboratory since late March, 2020. The samples are representative across age groups and health regions, and are de-identified before testing to protect the privacy of the individuals. This means individuals whose samples have been tested for COVID-19 antibodies cannot be identified and will not be informed of test results. This approach to sample collection is being widely used for various COVID-19 serosurveillance initiatives across Canada, and was reviewed and endorsed by PHO’s Research and Ethics Board as well as the COVID-19 Ethics Table.
We are also collaborating with the World Health Organization (WHO) and will contribute our ongoing serosurveillance results to WHO Unity Studies. Our results will also be made available to the Canadian COVID-19 Immunity Task Force.