Testing for COVID-19
Why testing is important
Most people who contract COVID-19 will recover; however, some people are at higher risk of complications. If you think you may have COVID-19, or if you have been in contact with someone who has COVID-19, you should contact your local health authority for advice about testing.
Knowing if you are infected is important for protecting:
- your family
- people you encounter
Testing for the presence of the virus is the only way we can confirm if someone currently has COVID-19.
Testing helps reduce the spread of the virus. When people are confirmed to have COVID-19, they can be isolated at home, or if needed, in a hospital.
Testing tells us:
- who has the infection
- where in our communities the virus is spreading
- how much the virus may be circulating in our communities
Testing is a key tool to:
- detect and isolate people who have COVID-19
- follow up with close contacts
- help us to better understand this virus
- inform the public health actions we take
- stop the spread of the virus and prevent outbreaks
Once someone is confirmed to have COVID-19, public health officials will interview them. This helps them to identify people that they may have been in contact with while they were contagious.
This is called contact tracing. It’s a key public health measure to slow down or stop the spread of the virus in our communities.
By tracking down their contacts, public health officials can tell individuals that they may have been exposed to the virus. Once identified, these individuals can then monitor themselves for symptoms, and follow recommended public health measures.
The Public Health Agency of Canada has developed guidance, through the federal, provincial and territorial COVID-19 Special Advisory Committee, to support a national approach to testing in Canada and to optimize the use of local resources in protecting the health of Canadians across the country. Each province and territory will determine individually how they implement this guidance, based on regional differences and local context.
See the number of people tested in Canada to date.
People with COVID-19 can have:
- mild symptoms
- severe symptoms
- no symptoms at all (also known as asymptomatic)
To decide who should be tested, health care professionals assess people based on their:
- underlying medical conditions
- risk of exposure to the virus
How we test for COVID-19
Currently in Canada, there are 3 ways of testing for COVID-19. Your health care provider will determine the right test for you.
Molecular PCR and point-of-care testing
Molecular PCR and point-of-care tests detect the virus and diagnose COVID-19. If you are being tested for a possible current case of COVID-19, you will receive one these tests.
Molecular PCR test
- uses swabs to collect samples from the nose or throat which are sent to a laboratory for testing
- results are ready in 1-3 days
- involves a rapid test done at the time and place of care, such as a hospital or doctor’s office
- uses swabs to collect samples from the nose or throat which are then tested on-site
- results are ready in 30-60 minutes
Since point-of-care technology can only test a limited number of samples in a single machine, it’s used in places where it’s needed most, including:
- rural, remote and isolated communities
- specific high-risk settings where it’s important to have fast test results without having to send samples to a laboratory
Antibody testing (serology)
Health care providers may have access to blood tests, called serological tests, which are used to see who may have already had the virus. These detect the presence of antibodies produced by your immune system in response to an infection. A positive serological test means that someone has been exposed to the virus in the past, but cannot reliably indicate how long ago that exposure occurred. As a result, they are not used to diagnose a case of COVID-19 in early stages of infection, since they don’t detect the virus itself.
Serological tests can help us:
- estimate how many people have had COVID-19
- determine which public health measures need to be in place
- better understand how much the virus has been circulating in the community
All tests must be performed by a health care professional. At-home sample collection test kits or home test kits have not been authorized for sale.
Test accuracy can vary during the course of your illness. For example, depending on when a test is conducted, it could result in false negative results if there’s not enough virus in your body at the time of the test. False positive results are also possible. Health care professionals make their diagnosis decisions based on a number of factors, including test results.
- A positive test means that you have COVID-19 and must follow public health measures.
- A negative test can indicate that a person is not infected, but it doesn’t always mean you’re COVID-19-free. If you’re tested too soon after exposure, the virus may not be detected because the person is still incubating the virus and it is not detectable at the time of the test and will ultimately become infectious.
- Sometimes tests are inconclusive. In this case, your health care provider may re-test you.
When to get tested
Public health authorities in every province and territory have developed their own
approaches for testing people, based on the local context in each area.
For information about COVID-19 testing in your area, contact your local public health authority.
How to get tested
If you think you might have COVID-19:
- try the Government of Canada’s self-assessment tool, or one of the self-assessment tools available from your province or territory
- connect with your local public health authority who can tell you how to get tested
Role of Health Canada in authorizing tests
As an emergency public health measure, Health Canada is allowing expedited access to COVID-19-related medical devices, including testing devices.
COVID-19 tests authorized by Health Canada are supported by evidence that they are accurate and reliable. More than a dozen COVID-19 testing devices are now authorized in Canada.
Only testing devices authorized by Health Canada can be imported or sold in Canada. Unauthorized tests may not produce accurate results, leading to potential misdiagnosis. Health Canada:
- assesses and monitors the safety and effectiveness of all medical products authorized for use related to COVID-19
- will take immediate action if required to protect the health and safety of Canadians
Role of the Public Health Agency of Canada’s National Microbiology Laboratory
The National Microbiology Laboratory is working with public health laboratories nationwide to:
- test specimens received from provinces and territories
- develop accurate tests
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