COLUMBUS, Ohio (WJW)– A doctor joined Ohio Gov. Mike DeWine‘s coronavirus news conference on Friday to explain the two types of testing for COVID-19.

DeWine was scheduled to meet President Donald Trump during his visit to Northeast Ohio on Thursday, but was unable to after a positive coronavirus test. The governor, who was not experiencing symptoms, returned to Columbus and planned to quarantine for 14 days, according to his office. Then, he tested negative.

So why the two different results? DeWine said the first test, performed at Case Western Reserve University, was an antigen test. The next test, which was conducted Thursday evening and sent to Ohio State, was a PCR test.

Dr. Peter Mohler, chief scientific officer for the Ohio State University Wexner Medical Center and vice dean for research at Ohio State College of Medicine, compared the antigen test to binoculars, while the PCR test is more like a high-powered telescope.

“Like binoculars, you’re going to miss a lot of stars,” Mohler said while appearing via video during the news conference.

Mohler said the antigen test doesn’t look at the genetic makeup of the virus, instead it examines the protein on the surface. Results are available in 15 to 20 minutes, but it can result in false positives and false negatives.

According to the doctor, the PCR test looks at the genetics and is very sensitive. He called it the gold standard.

“The PCR test we ran last night is by far more accurate and in fact, we ran it twice. We ran it on a duplicate piece of equipment and got the same information. We fully stand by the data we created last night,” Mohler said.

He said both tests are part of a toolbox.

DeWine said the experience forced him to think more about the testing available to residents in the state.

“The majority of Ohioans, we don’t know the exact number but well over 90 percent, the test they got was the PCR test, which is the test I ended up with at Ohio State. What it does say to me, having to drill down the difference between these two tests and understand it better, is that when we deploy an antigen test, we have to think about long and hard about how exactly we’re going to deploy it,” DeWine said.

“We also know the reliability is not nearly as good as the PCR test that most Ohioans have had.”

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