Doctor explains different types of COVID-19 tests, explains why Gov. DeWine tested positive and negative


COLUMBUS, Ohio (WCMH) — During Friday’s coronavirus briefing, Gov. Mike DeWine addressed the state from his home in Cedarville, Ohio. He stayed at home because on Thursday he tested positive for the coronavirus minutes before meeting President Trump on the tarmac at Burke Lakefront Airport in Cleveland. 

But later that day, DeWine tested negative for the coronavirus.

Gov. DeWine received an antigen test Thursday morning when he tested positive, and he received a PCR test Thursday night when he tested negative.

To explain the discrepancy between those two tests and other types of tests, Gov. DeWine was joined by Dr. Peter Mohler, chief scientific officer for The Ohio State University Wexner Medical Center and vice dean for research at the OSU College of Medicine.

DeWine said Dr. Mohler has been working with his team for the past few months to help with Ohio’s testing strategies.

“What happened with me yesterday has caused some questions,” DeWine said.

Dr. Mohler said PCR tests, which came back negative for DeWine, is what’s been widely used across Ohio throughout the pandemic with roughly 1.6 million PCR tests performed in Ohio.

“This is an incredibly sensitive and incredibly accurate test. It’s like a big telescope way to look at the virus,” Dr. Mohler said. “We would call the gold standard the PCT test.”

Dr. Mohler said the advantages of the PCR test are that it looks at the genetic makeup of the virus, makes it possible to detect very low viral loads in people that are symptomatic or asymptomatic, and it gives doctors the ability to look at the virus over time, which means doctors are very familiar with the strengths and weaknesses of a PCR tests.

He said the disadvantages of the PCR test are that it’s hard to scale and it takes a certain type of person to be able to run them who’s had the necessary training.

“The antigen test doesn’t look at the genetic material, it looks at the protein on the surface of the virus,” Dr. Mohler said. “It’s a little bit less sensitive and so you’re going to have things that we call false negatives and false positives.”

Dr. Mohler said the advantage of the antigen test is that it’s possible to have lots of those types of tests across the field and it allows for point of care testing, which means results can come back within 15 or 20 minutes.

“For the epidemiologists of the world, you’re very quickly able to do contact tracing, be able to quarantine people and be able to make decisions on healthcare,” Dr. Mohler said.

But Dr. Mohler added there are a lot of unknowns about antigen testing because it’s a relatively newer type of test.

Dr. Mohler went on to say there are two types of quick tests that can be done within 15 or 20 minutes. The first type is the antigen test, which is a swab of person’s throat or nose and gets puts in a machine to find out if that person is positive or negative for the coronavirus.

He said the other quick test is an Abbott point of care test, which is still a molecular test like the PCR test detecting the DNA of the virus and it’s often done in the emergency departments as a way to triage cases.

“It’s still a very accurate test but not quite as accurate as what we would do . . . here at the Wexner Center with Battelle,” Dr. Mohler said.

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