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Viral Test for COVID-19

Test Overview

Note: This information is only about the test to diagnose COVID-19. It’s not about tests (such as a COVID-19 antibody test) that show if you had COVID-19 in the past.

A COVID-19 test is a way to find out if you have COVID-19. It's a viral test that looks for COVID-19 virus in samples (such as swabs) from your nose or throat (breathing passages). There are different types of viral tests:

  • A polymerase chain reaction (PCR) or nucleic acid test looks for genetic material from the virus.
  • An antigen test looks for proteins on the virus.
  • ID NOW is a test that looks for COVID-19 genetic material in a different way than the PCR test. It’s similar to antigen tests.
The antigen test and the ID NOW are not as accurate (correct) as PCR. People who get an antigen or ID NOW test will need to have 2 swabs collected.

Antigen and ID NOW test results come back in a few hours. PCR tests may take a few days. Faster PCR testing or ID NOW testing is done for people who are very sick and need hospital care.

If you have questions about COVID-19 testing, ask your doctor or your local or provincial health authority.

Why It Is Done

This test is used to diagnose a current infection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19). Knowing that you have the virus means that you can take steps to protect others from getting infected. This can help limit the spread of the virus.

How It Is Done

The test is most often done on a sample from the back of your nose (nasopharyngeal) or throat. A sample is usually collected by putting a swab into the back of your nose. If you agree to have an antigen or ID NOW test, you will have 2 samples collected. The first is used for antigen or ID NOW testing. The second is sent to the lab to confirm a negative result with PCR testing or, if the antigen test is positive, test for COVID-19 variants.


A PCR result is either positive or negative. An ID NOW or antigen test result is reported as either positive or result to follow.

A positive result means that the antigen or genetic material of the virus was found in your sample. You have been diagnosed with COVID-19.

Result to follow means that the antigen or genetic material of the virus wasn’t found in your sample. But your sample needs more testing before confirming the test is negative for COVID-19.

A negative result means that the antigen or genetic material was not found. This may mean that you don't have COVID-19.

But it's possible to get a "false-negative" result. This may mean that you don't have COVID-19 when in fact you do. This may happen because:

Because false negative results sometimes happen, you should continue isolating if you have symptoms and follow all public health measures. If you are a close contact of someone who has COVID-19, you should monitor yourself for symptoms for 7 days after your last exposure. Where possible, avoid close contact with vulnerable people.

  • You were tested too early (before the virus got to high enough levels in your nose or throat).
  • You were tested too late (after your immune system fought off the virus).
  • The swab didn’t reach the infected area.

If you get a negative result for an antigen test, your doctor may recommend that you get another test, such as polymerase chain reaction (PCR), to make sure you don't have the virus. You may need to take the same test again to make sure you don't have the virus.

Waiting for your test results

While you wait for your COVID-19 test results, stay in your home, and stay away from others. This is called isolation or quarantine. Don't leave unless you need medical care. If you can, try to stay in a separate room. This might help you avoid infecting family members or other people you live with.

Follow your doctor's instructions about what to do when you get your results back.

Related Information


Adaptation Date: 4/5/2023

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

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