Testing for COVID-19

Two kinds of tests are available for COVID-19: diagnostic tests and antibody blood tests. Diagnostic tests check samples from your respiratory system (such as swabs of the inside of the nose) to tell you if you currently have an infection with SARS-CoV-2, the virus that causes COVID-19. Antibody blood tests, also known as serologic tests, check your blood for antibodies that would show if you have had a previous infection. Antibodies are proteins that help fight off germs. A serologic test may not be able to show if you have a current infection, because it can take 1 to 3 weeks to make antibodies after symptoms occur.

If you test positive or negative for COVID-19, no matter the type of test, you still should take preventive measures to protect yourself and others.

Diagnostic Testing

Diagnostic tests can find the virus that causes COVID-19 in samples taken from your respiratory system, such as swabs of the inside of your nose. Some tests are point-of-care tests, meaning results may be available at the testing site in less than an hour. Other tests must be sent to a laboratory to analyse, a process that takes 1-2 days once received by the lab.

How to decide if you should get a diagnostic test

Not everyone needs to be tested for COVID-19. Here is some information that might help you make decisions about getting a diagnostic test.

• Most people have mild illness and can recover at home without medical care. They may not need to be tested.
• At this time, there is no treatment specifically approved for people who have COVID-19.

What to do after a diagnostic test

To get your test result, please check with the group that performed your test, such as your healthcare provider or your health department.

• If you test positive for COVID-19, know what protective steps to take.
• If you test negative for COVID-19, you probably were not infected at the time your sample was collected. Know-How to Protect Yourself and Others.

Serologic (Antibody) Testing

Antibody blood (serologic) tests, check your blood by looking for antibodies, which show if you had a previous infection with the virus. Depending on the time of infection and the timing of the test, the test may not find antibodies in someone with a current COVID-19 infection. Antibodies are proteins that help fight off germs. Serologic tests should not be used as the only way to diagnose someone as being currently sick with COVID-19.

• If you test positive:
• A positive test result shows you have antibodies that likely resulted from infection with SARS-CoV-2, or possibly a related coronavirus.
• It is unclear if those antibodies can provide protection (immunity) against being infected again. This means that we do not know at this time if antibodies make you immune to the virus.
• If you have no symptoms, you likely do not have an active infection and no additional follow-up is needed.
• If you have symptoms, you would need another type of test called a nucleic acid test. This test uses respiratory samples, such as a swab from inside your nose, to confirm COVID-19. A serologic test alone cannot tell if you definitely have COVID-19.
• It is possible you might test positive for antibodies and you might not have or have ever had symptoms of COVID-19. This is known as having an asymptomatic infection (without symptoms).
• If you test negative:
• If you test negative for COVID-19 antibodies, you probably did not have a previous infection that has gotten better. However, you could have a current infection. It is possible you could still get sick if you have been exposed to the virus recently since antibodies do not show up for 1 to 3 weeks after infection.
• Some people may take even longer to develop antibodies, and some people may not develop antibodies.
• If you have symptoms, you would need another type of test called a nucleic acid test. This test uses respiratory samples, such as a swab from inside your nose, to confirm COVID-19. A serologic test alone cannot tell if you definitely have COVID-19.
• Know-How to Protect Yourself and Others.