Diagnosing COVID-19

There are two kinds of tests available to diagnose COVID-19: tests for current infection (viral tests) and tests for past infection (antibody tests). The tests each perform a separate function. Your doctor may order a viral test to diagnose your illness if they suspect that you have COVID-19. If your doctor believes you were previously infected, they may order an antibody test to confirm.

Viral Tests

Viral tests use respiratory samples, such as a swab from inside your nose, to determine if you are currently infected with SARS-CoV-2, the virus that causes COVID-19. Depending on the testing site, results may be available within a few hours or may take several days if the sample is sent to a laboratory for analysis.

If you think you have been exposed to the virus and are exhibiting symptoms, speak to your healthcare provider to determine if you should be tested. The Centers for Disease Control and Prevention (CDC) has developed guidance for who should be tested, including:

  • Individuals with signs or symptoms of COVID-19
  • Individuals with no symptoms (are asymptomatic) with known or suspected exposure to SARS-CoV-2
  • Individuals with no symptoms (are asymptomatic) without known or suspected exposure to SARS-CoV-2 for early identification in certain settings (such as nursing homes)
  • Individuals being tested to determine resolution of a prior positive test
  • Individuals tested for purposes of public health surveillance

Results from your viral test will indicate that you either:

  • Test positive for COVID-19 with next steps including monitoring your symptoms, watching for emergency medical signs, engaging in home isolation and maintaining close communication with your healthcare provider.
  • Test negative for COVID-19, which means you were not infected at the time the sample was collected and analyzed. This doesn’t mean that you won’t get sick, only that you didn’t have COVID-19 when you were tested. You can think of this like a single snapshot in time that doesn’t determine if you had COVID-19 previously or if you will be exposed and infected in the future. If you later experience symptoms, or have close contact with an infected individual, you should speak with your doctor to determine if you need another test.

Find a Testing Site

The U.S. Department of Health & Human Services has a COVID-19 testing site locator if you need to find a testing site near you. The Families First Coronavirus Response Act ensures that COVID-19 testing is free to anyone in the U.S.

Antibody Tests

Antibody tests are performed by drawing blood and conducting a laboratory test to check for antibodies that would only be present if you had a past infection of SARS-CoV-2, the virus that causes COVID-19. An antibody test should not be used to determine current infection as it can take your body one to three weeks after infection to make antibodies.

If you think you were previously infected with COVID-19, you should speak with your doctor about your symptoms or exposure to infected individuals.

Results from your antibody test will indicate:

  • If you test positive you were previously infected with COVID-19. You should continue to take steps to prevent a future COVID-19 infection. Researchers do not yet know if you are protected from being infected again.
  • If you test negative you have likely not been previously infected with COVID-19. You should continue to take steps to prevent a future COVID-19 infection.

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: January 29, 2021

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