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’s new with COVID-19 Laboratory Testing in Ontario?

Ontario has a robust surveillance system for monitoring current COVID-19 variants circulating in Ontario and for detecting and identifying new and emerging variants, including the Omicron (B.1.1.529) variant. The Ontario COVID-19 Genomic Network (OCGN), which includes the labs at PHO, Sick Kids, Kingston General Hospital, Shared Labs and Hamilton Health Sciences, is continuing to actively monitor for all potential variants circulating in the province.

  • 100% of positive samples will continue to be sequenced through whole genome sequencing as per current provincial surveillance activities. This percentage should provide a representative sample of the characteristics of the tested population.

For more information about laboratory testing for variants, please visit our Laboratory Testing to Monitor for COVID-19 Variants page.

What type of COVID-19 testing does PHO do?

PHO performs thousands of COVID-19 diagnostic tests every day 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?

There are two primary methods used in Ontario for COVID-19 diagnostic testing:

  1. PCR testing (also known as polymerase chain reaction 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.

  2. Serology testing tests someone’s blood to see if they have antibodies for COVID-19. This primarily tells us if someone previously had COVID-19. Currently this test is used in limited clinical situations.

Find out more about the difference between these two types of tests and their application.

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 cannot 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.

Adapting to Future Needs

We work with the Ministry of Health, Ontario Health and other key experts and stakeholders to monitor, provide guidance, and strategize to make sure COVID-19 testing in the province continues to respond to this evolving public health emergency. We explore new test methodologies, like serology, and continue to investigate and validate the use of different types of swabs, reagents, and testing platforms so that our approach can be flexible.


PHO Microbiology Rounds: CRISPR Diagnostics for Tackling Antimicrobial Resistance

This PHO Microbiology Rounds will present on new diagnostic sensors at the interface of cell-free synthetic biology, next generation micro/nanoscale sensing systems, and engineering design for clinical and commercial translation.

See the Event Details
Updated 23 Feb 2022