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.

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.

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 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. Sometimes these tests need to be repeated if they show a negative result to best detect infection.  

If you think you are exhibiting symptoms of COVID-19, get tested right away. Take the CDC’s COVID-19 Viral Testing Tool or read below.

You should get tested for COVID-19 if you:

  • 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.

What type of COVID-19 test to use: 

  • 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.  
  • Talk to your healthcare provider if you have any questions or concerns about your test results.  

Results from your viral test will indicate that you either:

  • Test positive for the virus that causes COVID-19. Learn more about next steps to take and ways to help prevent the spread of disease to others.
  • Test negative for COVID-19.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.

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.
Learn more

Steps to take if you were exposed to COVID-19

If you were exposed to the virus that causes COVID-19, there are the steps you should take. You can develop COVID-19 up to 10 days after exposure, these steps should be taken for the full 10 days. CDC has developed a website to better understand exposure risks.   

Step 1

Wear a high-quality mask or respirator (ex. N95) mask as soon as you find out you were exposed. Start counting from day 1, the first full day after exposure.

Step 2

Test 5 full days after exposure or sooner if symptoms emerge.

Step 3

Watch for symptoms of COVID-19. 

If you develop symptoms, you should: 

  • Isolate right away 
  • Test 
  • Stay home until you know the test result (follow these steps for a positive test result) 

Step 4

Take extra precautions if you are around people at increased risk for severe COVID-19 illness. This includes older adults, individuals who are immunocompromised and individuals who have certain underlying health conditions.  

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.

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

Page last updated: November 18, 2022

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