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COVID-19 Viral Test: About This Test

What is it?

Note: This information is only about the test to diagnose COVID-19 at Alberta Health Services health facilities (like hospitals) or assessment (swab) centres. For information about home antigen testing, see rapid testing at home. This information is also 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) taken from breathing passages, like your nose or throat. 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.
  • An ID NOW is similar to antigen tests and looks for COVID-19 genetic material in a different way.

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

Why is it 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.

Knowing who has COVID-19 is also important for public health experts who track the virus. It can help them learn more about how the virus spreads and how to stop it from spreading.

How do you prepare for the test?

You don't need to do anything to prepare for this test. But be sure to follow any instructions your health care provider gives you.

How is it done?

The test is most often done on a sample from your nose (nasopharyngeal) or throat. One way a sample is collected is by putting a long swab into the back of your nose.

What should you do while you wait for your test results?

While you wait for your COVID-19 test results, if you have symptoms, you should stay in your home, and stay away from others. This is called isolation. 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 or visit ahs.ca/results for information about what to do when you get your results back, even if the test is negative.

What do your results mean?

A PCR or ID NOW result is either positive or negative. In hospitals, the ID NOW result may be reported as positive or result to follow with a follow-up PCR test done.

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

Result to follow means that the antigen or genetic material of the virus was not 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 the genetic material was not found. This may mean that you do not have COVID-19.

It is possible to get a "false-negative" result. This may mean that the test result says you do not have COVID-19 when in fact you do. This can happen because:

  • You were tested too soon (before the virus got to high enough levels in your nose and throat).
  • You were tested too late (after your immune system fought off the virus).
  • The swab did not reach the infected area.

Because a false negative result is possible, continue to isolate if you have symptoms. Follow all public health measures.

For information about when you may need to isolate, go to: COVID-19 Isolation & Quarantine Information | Alberta Health Services.
For 24/7 nurse advice and general health information call Health Link at 811.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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Adapted with permission from copyrighted materials from Healthwise, Incorporated (Healthwise). This information does not replace the advice of a doctor. Healthwise disclaims any warranty and is not responsible or liable for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.