COVID-19 testing scenarios — what test and when?

Mayo Clinic Q&A

Testing for COVID-19 is a part of the strategy to end the pandemic. But understanding testing — different types of tests and how and when to use them — can be confusing. Lab-run polymerase chain reaction, or PCR, tests and at-home antigen tests each have a role.

"PCR tests are really sensitive, meaning we can detect really low levels of the virus in a sample," explains Dr. Matthew Binnicker, director of Clinical Virology at Mayo Clinic. "They're very specific, meaning we shouldn't get many false positive results with PCR tests."

At-home antigen tests use a nasal swab and can produce results in 15 minutes, but they also have an increased chance of false-negative results, depending on when you test.

"At-home rapid antigen tests look for a viral protein in the patient sample," says Dr. Binnicker. "So they're quick and easy, but they also have some important limitations."

So if you're worried you might have COVID-19, what test should you take and when?

On the Q&A podcast, Dr. Binnicker walks through various scenarios and makes testing recommendations for what to do if:

• You think you’ve been exposed but I don’t have symptoms.
• You have symptoms of COVID-19.
• You had COVID-19 and want to know if you're “in the clear” to return to work, school or activities.