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Antibody Test for COVID-19


An antibody test (also called a serology test) looks for antibodies in the blood. These are proteins that your immune system makes, usually after you're exposed to germs like viruses or bacteria or after you get a vaccine. Antibodies work to fight illness.

A COVID-19 antibody test looks for antibodies to SARS-CoV-2, the virus that causes COVID-19. If you test positive for these antibodies, it could mean that you already had COVID-19. If you’ve had the COVID-19 vaccine, it’s not yet known how the vaccine will affect the antibody test results.

Most people don’t need this test. Antibody testing is mostly used to help track the virus, and the test is not commonly done in Alberta. These test results still mean that everyone must follow all public health measures to help stop the spread of COVID-19.

This test can be used to diagnose a past infection with the virus that causes COVID-19. This test is not useful for finding out if you have COVID-19 now because it can take weeks for your body to make enough antibodies to show up on the test. Other testing that directly detects the virus, like viral testing (or nucleic acid testing), is used to diagnose new COVID-19 infections.

Antibody testing is useful because:

  • A positive result shows that you’ve already had COVID-19. But even if you have the antibody against SARS-CoV-2, you’re not considered immune to the virus. Keep doing things like wearing a mask, washing your hands often, and practising physical distancing.
  • It could show who hasn't had COVID-19. Even though a negative result shows that you haven’t been infected, you’re still at risk. Keep taking steps to protect yourself from the virus.
  • It helps experts who are tracking COVID-19 learn more about the virus and how it spreads.

Talk to your doctor about what the test results mean for you.

This is a blood test. A health professional will use a needle to take a sample of blood from your arm.

Related Information


Adaptation Date: 7/8/2021

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

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