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  5. COVID-19 Testing and Diagnosis

COVID-19 Testing and Diagnosis

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). Learn more about these types of tests, when you should get tested for COVID-19 and what to do after your test results.

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Testing for COVID-19

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If you begin experiencing symptoms that could be COVID-19, it is important to test right away. There are many other respiratory viruses that spread at the same time, particularly in the fall and winter. Knowing which infectious respiratory disease you have can help determine the right treatment for you. COVID-19 tests are widely available at pharmacies nationwide.

Visit Lung.org/COVID-19 for more information.

Need Help Finding Testing for COVID-19?

You can order four free at-home COVID-19 tests at the end of September.
Order tests
The Centers for Disease Control and Prevention (CDC) has a COVID-19 testing site locator if you need to find a testing site near you.
Use the Locator

Viral Tests

Viral tests look for a current COVID-19 infection. They use respiratory samples, such as a swab from inside your nose or saliva from your mouth, 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 minutes, a few hours or may take several days if the sample is sent to a laboratory for analysis.

  • NAATs, such as PCR tests are most often performed in a laboratory. These tests may continue to show a positive result for some time, so they should not be used if you have tested positive in the last 90 days.
  • Antigen tests or at-home tests are rapid tests and produce results quickly. Antigen tests are less likely to detect the virus than NAAT tests, especially when people do not have symptoms. To be confident that the test is negative, it is recommended that individuals who have symptoms repeat the test 2 times and individuals with no symptoms repeat the test 3 times (48 hours apart).

If you think you are exhibiting symptoms of COVID-19, get tested right away. Visit the CDC’s webpage for choosing a COVID-19 test or read below.

  • Are experiencing symptoms of COVID-19, test right away.
  • Were exposed to COVID-19 and do not have symptoms.
    • At least 5 days after exposure with day 0 being the day of contact. While you are waiting on test results, quarantine from others to limit the possibility of disease spread.
  • Have been asked or referred to get tested by your school, workplace, healthcare provider, or state, local, tribal or territorial health department.
  • Are visiting someone at high risk for severe COVID-19 illness.
  • If you have not had COVID-19 or a positive test within the past 90 days: 
    • You may use either a NAAT or antigen test.  
  • If you tested positive for COVID-19 in the last 90 days: 
    • If the positive test was within 30 days and you have symptoms, use an antigen test.
    • If the positive test was within 30 days and you do not have symptoms, testing is not recommended.
    • If the positive test was within 31-90 days and you have symptoms, use an antigen test.
    • If the positive test was within 31-90 days and you do not have symptoms, use an antigen test.  
  • Because some tests may show positive results up to 90 days, and reinfections can occur in 90 days, it can be challenging to know if a positive result indicates a previous infection or a new infection. Talk to your healthcare provider if you have any questions or concerns about your test results.  

Interested in performing a COVID-19 test at home? This short video from the CDC explains the basics of how to purchase a self-test, collect a specimen, perform the test, and dispose of the test.

Results from your viral test will indicate that you either:

  • Learn more about next steps to take and ways to help prevent the spread of disease to others.
  • Monitor your symptoms and seek immediate care if you have any emergency warning signs.
  • Speak with your healthcare provider about treatment options if you are at high risk for severe COVID-19 illness.

This means that the test did not detect the virus at the time you took the test, you could still have COVID-19. 

  • If you have symptoms of COVID-19, you might have tested before the virus was detectable and could still have COVID-19 so you should still isolate from others to avoid spreading the virus. Contact your healthcare provider about your symptoms, especially if they get worse, about further testing and how long to isolate. 
  • If you do not have symptoms of COVID-19, you are likely not infected but you could still get sick.
    • Continue taking recommended steps after COVID-19 exposure.
    • If you do not have symptoms and you have not been exposed to COVID-19, no further action is needed.
  • If you later experience symptoms, or have close contact with an infected individual, you will need to test again.
  • If you tested negative with one antigen or at-home test, it is recommended to repeat testing to be sure that you do not have COVID-19.

What to Do If You Test Positive

If you test positive for COVID-19, there are things you need to do to take care of yourself and help stop the spread of disease to others.

Antibody Tests to Detect Past Infection

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.

Antibody testing is not recommended to determine immunity or whether you need to get vaccinated.

Results from your antibody test will be positive if you were previously infected with COVID-19 and negative if you have not been previously infected. Regardless of the status of your test, you should take steps, including getting vaccinated, to protect against COVID-19.

Previous: COVID-19 Symptoms
Next: COVID-19 Treatment

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

Page last updated: September 4, 2024

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