COVID-19 Testing: What Is the Antigen Test?

If you took a “rapid” test, it was likely an antigen test.

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Something came up, and now you need a COVID-19 test result in under an hour. With so many asymptomatic cases, testing is essential to know your status and prevent the spread of COVID-19 to others. There are different types of tests available, and the best option when you’re in a hurry is currently the antigen test.

How the Antigen Test Works

The antigen test is a diagnostic test, meaning it can diagnose if you have COVID-19 now (or not). It works by detecting specific proteins (antigens) from the virus. Usually, this test is a nasal swab test.

Most commonly, the antigen test is known as the rapid COVID-19 test. However, there are other types and methods:

  • Rapid: A mucus sample is collected from the nose. Then, a technician analyzes it either in the doctor’s office, or at the testing site. Often, results are available within minutes.
  • Combination test: This can test for influenza and COVID-19 at the same time. This is useful since symptoms and COVID-19 and the flu can be very similar.
  • At-home collection: There are self-test kits available that allow you to collect the sample at home. Some require you to send the sample to a lab for analysis. Others will give you a result within minutes.

It’s important to know that antigen tests are less accurate than PCR tests. It’s more prone to false negatives—meaning your test results will say negative even though you actually have COVID-19. This is why it is important to confirm your results with a PCR test, especially if you are having symptoms or know you have been exposed to someone who tested positive.

Who and When Should You Get Tested

You should get tested if you:

  • Go to public places frequently
  • Have a job that requires you to interact with others
  • Are showing any COVID-19 symptoms

After potential exposure, wait 5 to 10 days before you get tested. If you test yourself too soon, you run the risk of getting a false negative because the virus hasn’t had a chance to develop in your body. Learn more about what a negative COVID-19 result means here.

If you test positive, isolate immediately and call your doctor so you can come up with a home care plan that is right for you. Learn more about what to do if you test positive for COVID-19 here.