What’s the difference between the 2 main types of COVID-19 tests?

27 Investigates

There's one doctors recommend more because of its accuracy

(WKBN) – After word Thursday that Ohio Gov. Mike DeWine tested positive for COVID-19, then negative after a second test later the same day, First News wanted answers.

Maybe until recently, you didn’t know there was more than one type of test for COVID-19. DeWine revealed he had taken more than one type of test — and each came back with a different result.

There are two main types of tests — PCR and antigen.

The PCR test is more accurate but takes longer, at least a few days, to get results.

“More of the send-out tests, that takes a little bit longer sometimes,” said Dr. Jim Kravec, with Mercy Health.

The antigen test, or rapid test, yields quicker results — an hour or less — but can be inaccurate.

“You can find out results within 15 or 20 minutes and so with the epidemiologists of the world, you’re very quickly allowed to do contact tracing, be able to quarantine people and be able to make decisions on health care,” said Dr. Peter Mohler, with the Ohio State University.

“Those are a little bit quicker and in turnaround, they may have a little less efficacy,” Kravec said.

Right now, about 90% of tests done in Ohio are PCR. That makes case numbers more accurate, but patients are waiting longer to get results.

DeWine’s first test before his planned meeting with the president Thursday was an antigen test, which showed he had COVID-19. Later that evening, he had a PCR test done, which came back negative for COVID-19.

Dr. Lena Esmail, with QUICKmed Urgent Care, has been doing PCR tests on patients since the pandemic started. In her opinion, the antigen test should always be followed up with a PCR test.

“That’s why we don’t do antigen tests here because ultimately…we would follow up as clinicians here with a PCR test either way, because they are the standard because of their high level of accuracy,” she said.

Esmail said the quick response of the antigen tests could cause issues later on.

“Letting their family and friends know that he or she was positive, and then having all those people subsequently tested or them being negative on the antigen test and actually being a positive patient and going out and infecting several other people.”

Even though doctors have said the PCR does a better job, Kravec explained no test is 100% accurate.

“Not just with COVID, but really with every test. The flu test was that way, other laboratory tests were that way. So this, actually, is common.”

For antigen tests, the results are counted differently. Someone who tests positive after an antigen test would be considered a “probable case,” not confirmed.

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