Testing devices for COVID-19: Serological testing devices
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- Types of testing devices for COVID-19
- Nucleic acid-based testing
- Serological testing
- What Health Canada is doing
Types of testing devices for COVID-19
The majority of submissions received by Health Canada are for 2 types of in vitro testing devices:
- nucleic acid-based tests (for detecting the virus)
- serological tests (for detecting antibodies)
Nucleic acid-based testing has proven to be a reliable method to diagnose COVID-19 infection by detecting the virus itself. Serologic tests can be useful in assessing people who contracted the disease by detecting the antibodies developed against the virus.
Health Canada is not aware of any serological-based test that has been validated for diagnosing COVID-19. However, serological tests will play an important role in Canada's overall testing strategy, providing evidence in assessing the true extent of COVID-19 in the general population.
Nucleic acid-based testing
Nucleic acid-based testing is also called PCR, or molecular testing. This test is the gold standard used in Canada and abroad to diagnose active COVID-19 infection in patients with symptoms.
Like most jurisdictions, Health Canada prioritized the review of diagnostic tests using nucleic acid technology. We did this to increase the number of testing devices available in Canada to diagnose active and early-stage infections of COVID-19.
We have authorized several nucleic acid diagnostic devices. Consult our list of authorized testing devices.
Serological tests do not detect the virus itself. Instead, they detect the antibodies produced in response to an infection.
Serological tests are not appropriate for early diagnosis of COVID-19. This is largely because of variability in the time required after infection to develop antibodies. However, Health Canada is now authorizing the sale in Canada of serological testing devices used for other purposes.
Understanding serological testing results
Serological testing detects the presence of antibodies, not the presence of the SARS-CoV-2 virus. This testing is also not to be used to diagnose infection.
The immune response to a virus involves the creation of different types of antibodies produced at different stages of an infection:
- early antibodies, called IgM antibodies, provide the first indication of the body's response to an infection
- these antibodies are not as specific and generally are not as long lasting, so interpreting their significance requires clinical experience
- IgG antibodies are specific to a virus, such as the SARS-CoV-2 virus
- early research results suggest these antibodies can be reliably detected 14 days after a person is infected with COVID-19
The relationship between antibodies and immunity to infection with SARS-CoV-2 is still unknown. It is unclear whether people with antibodies are immune to re-infection or if they are still infectious to others.
The sensitivity of serological testing in elderly or immuno-compromised people is unknown. This is because their age or condition can have an impact on their body's immune response.
Also, antibodies are present for an undetermined period of time after an infection has ended.
For the above reasons, serological test results should be interpreted with caution.
We follow the guidance on serological antibody test requirements, submitted under the COVID-19 interim order, when reviewing serological technologies. Those serological tests that show high sensitivity and specificity will be eligible to be authorized. However, we will not authorize products that do not have enough evidence of effectiveness. Product information must demonstrate the product is safe and effective.
In accordance with the guidance, we will be placing a 'condition' on all authorized serological tests. This action will allow us to monitor performance once the technology is in use in Canada.
For serological test requirements, please consult the requirements for serological antibody tests guidance and the notice on sensitivity and specificity values for COVID-19 serological testing devices.
What Health Canada is doing
We are committed to authorizing reliable technologies. We will continue to work with our federal, provincial and international regulatory partners to understand the emerging science on serological testing devices for COVID-19.
Our position concerning serological assays is in line with the World Health Organization. While serological assays will play an important role in research and surveillance, they are not currently recommended for diagnosis.
We will continue to collaborate with the National Microbiology Laboratory and our provincial public health laboratory partners. We will also leverage studies on immune responses and serological technologies in Canada and internationally. The authorized uses for serological technologies will depend on the type of evidence that we receive from manufacturers and from these studies.
Health Canada will continue to keep Canadians informed as new or additional information becomes available.
For more information on the authorization of medical devices for use against COVID-19, including how to submit an application, please consult medical devices for uses related to COVID-19.
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