COVID-19 Laboratory Testing at Public Health Ontario

Laboratory testing is an essential component of Ontario’s response to COVID-19. Not only because it tells us if someone has COVID-19 or not, but also because it sheds light on where and how the virus is spreading.


What type of COVID-19 testing does PHO do?

PHO performs COVID-19 diagnostic tests in partnership with many hospital, academic and private labs across the province. This network of labs, coordinated by Ontario Health, came together in early 2020, in order to meet the increased demand for testing.

PHO also acts as Ontario’s reference laboratory for COVID-19 testing. This means that we provide support to new labs as they come online with testing and also validate early samples from those labs to confirm the accuracy of the testing. We also validate new test methods (in collaboration with partner labs, including the National Microbiology Lab) and provide expertise to inform the evolution of Ontario’s testing strategy, including how these new methods are implemented.

PHO also leads the Ontario COVID-19 Genomics Network (OCGN), which was established in March 2021 in response to the emergence of COVID-19 variants, with the goal of providing timely surveillance of known and emerging variants. The OCGN is comprised of representatives from clinical and public health laboratories undertaking genomics testing, government, public health and research centres.

How is diagnostic testing for COVID-19 done?

The primary method used in Ontario for COVID-19 diagnostic testing is PCR testing (also known as polymerase chain reaction testing). PCR testing is a type of test that tells us if someone currently has COVID-19. It uses a sample collected with a swab from the person’s nose/throat.

How are COVID-19 variants detected in Ontario?

As new and emerging variants become known, laboratory systems around the world, including our lab at PHO, are required to adapt and shift to proactively monitor for these variants and understand how they are spreading in Ontario. The province’s complete variant testing and surveillance strategy includes three key components:

  • COVID-19 diagnostic testing (through PCR)
  • Whole genome sequencing

For more information, visit our Testing to Monitor COVID-19 Variants page.

Who should be tested for COVID-19?

If you have been in contact with or exposed to someone who has tested positive for COVID-19, take the Ontario COVID-19 self-assessment to determine next steps for you and the people in your household. More information on what to do if you have been exposed to COVID-19 is available at

If you are required to isolate, you should not leave your home for any reason unless you are going to get tested for COVID-19 or have an emergency. For more information, see our How to Self-Isolate Fact Sheet and follow current public health advice on how long to remain isolated.

Updated 22 Jan 2024