Importantly, they were different kinds of tests.
Ohio Gov. DeWine tests negative for COVID-19 hours after testing positive (Fox News)
How Accurate Are Virus Tests? Ohio Governor’s Results Show Positives and Negatives (New York Times)"The PCR tests for the Governor, First Lady, and staff were run twice," the statement said. "They came back negative the first time and came back negative when they were run on a second diagnostic platform."
His office said the PCR test was different than the rapid antigen test administered earlier in the morning as part of the standard protocol required to meet with Trump.
"We will be working with the manufacturer to have a better understanding of how the discrepancy between these two tests could have occurred," the statement added.
With testing delays nationwide, experts are increasingly recommending a new type of rapid test that gives less accurate results. It is imperfect, but as one expert put it, “pretty good is a lot better than none.”
At issue are two types of coronavirus tests that are increasingly taking center stage as part of the virus response in the United States. As part of a screening by the White House, Mr. DeWine first received an antigen test, a newer type of test that provides faster results but is less accurate than traditional laboratory testing. He was later tested using a more standard procedure known as polymerase chain reaction, or P.C.R., an accurate but time-intensive method that requires samples to be processed at a laboratory.
PCR tests, while more accurate than the antigen test, can take many days for the results to get back due to laboratory backlogs. In those days, waiting for the results, if the person isn't quarantined while awaiting the results, they could be out spreading the virus. So there is an advantage to learning the results quickly. The downside is less accuracy.Experts say results are needed within 24 to 48 hours to effectively quarantine and contact trace. In the United States, turnaround times are often stretching three to five days, or more.
How accurate are the results?
All virus tests have the possibility of an inaccurate result. “It is just a fact of clinical testing,” said Dr. Miller, who recommended using common sense about the risk of exposure when evaluating unexpected results.
But antigen tests are generally less sensitive and less accurate than the traditional nasal swab, laboratory test. Interestingly, antigen tests are more likely to produce false negatives — missing someone who has the virus — than false positives, the opposite of what appears to have happened to Mr. DeWine.
So false negatives, not just false positives, are an issue with these tests. And even the more reliable PCR tests are not necessarily 100% accurate.the tests could produce false negative results between 15 and 20 percent of the time.