Coronavirus confusion: Why mistakes more likely with DeWine’s first test


By Sabrina Eaton - cleveland.com (TNS)



Ohio Gov. Mike DeWine acknowledges members of the media while entering his residence after testing positive for COVID-19 earlier in the day Thursday, Aug. 6, 2020, in Bexley, Ohio. DeWine tested positive using a rapid test Thursday, before testing negative later in the day using a more sensitive laboratory-developed test. No test for coronavirus infection is perfect, and test results can be affected by a variety of factors, including the type of test used, the quality of the sample and when it was taken during the course of any infection.

Ohio Gov. Mike DeWine acknowledges members of the media while entering his residence after testing positive for COVID-19 earlier in the day Thursday, Aug. 6, 2020, in Bexley, Ohio. DeWine tested positive using a rapid test Thursday, before testing negative later in the day using a more sensitive laboratory-developed test. No test for coronavirus infection is perfect, and test results can be affected by a variety of factors, including the type of test used, the quality of the sample and when it was taken during the course of any infection.


AP Photo/Jay LaPrete

WASHINGTON, D.C. — Ohio Gov. Mike DeWine startled the state on Thursday afternoon when he disclosed that a coronavirus test the White House set up for him to take before he could meet President Donald Trump in Cleveland was positive. Nine hours later, DeWine startled the state again by divulging that he tested negative for the disease in a more sensitive test he subsequently took at Columbus’ Wexner Medical Center.

At a press briefing on Friday, DeWine described the previous day’s events as “a rollercoaster” and said he was “very happy, obviously,” that he does not seem to have the potentially lethal virus. Nonetheless, his office said that he and First Lady Fran DeWine plan to have another screening test for the COVID-19 virus on Saturday to be safe.

DeWine’s rapid-fire conflicting medical test results generated questions about the accuracy of the tests administered to the state’s chief executive, as well as some 1.3 million tests administered so far to screen other Ohioans for the potentially lethal virus.

At DeWine’s briefing, Wexner’s Dr. Peter Mohler compared the different tests that DeWine took to binoculars vs. a high powered telescope. He likened the low-cost, quick turnaround antigen test from Quidel that a Republican National Committee vendor administered at a pop-up, mobile testing site to binoculars. They’re less sensitive and will produce more false positives and more false negatives than the better test, but are easier to provide. He compared the second test DeWine took to a “high powered telescope” that takes more expertise to operate, but when results come in, “you get a very good impression of what’s happening at that level.”

Case Western Reserve University infectious disease expert Mark Cameron described antigen tests of the type that DeWine took before his planned meeting with Trump at Burke Lakefront Airport as “quick and dirty.” They’re less sensitive and less accurate than the other tests, with a three percent false positive rate. Businesses and sports leagues favor them because they usually provide results within an hour. They detect a specific protein that the virus has on its surface, called an antigen, and results appear as a color change on a testing stick, like home pregnancy tests.

Positive test results on the antigen test are usually double checked by taking the “gold standard” Polymerase Chain Reaction (PCR) test that DeWine took later in the afternoon, says Cameron. That test, which detects genetic material specific to virus that causes COVID-19, is the one Ohioans usually receive when their doctors test them for the virus. Its results are more accurate than the other test, but they take longer to deliver because the tests are processed by a lab.

The PCR test doesn’t produce false positives, but can produce false negatives if it is administered before viral loads have built up within the first week of infection, said Cameron. Although DeWine’s test results were returned within hours, most people who take that test must wait several days for results. The wait can result in asymptomatic people spreading the disease before their results are in, says Cameron. DeWine said he decided to expedite his own test results to keep himself from being confined for a long time in quarantine while awaiting them.

Both tests are administered with nasopharyngeal swabs that touch the back of the nose, because that’s where the highest viral concentrations are found. Cameron said the virus typically infects the nasal passages first, then spreads along the back of the throat to the lungs. And both types of tests are more available than they were when tests were scarce in the early days of the virus, only being used for the most vulnerable people in the community.

He said Ohio currently has about a 5 percent positive test rate, while states like Arizona and Florida have a 20 percent positive rate, which means that “if you consider going out in Florida or Arizona, one in five individuals you might run into could be harboring the virus.

“We are testing more and more people, and are closer to knowing more about the presence of the virus in the community through these testings,” said Cameron. “If the pandemic is under control, the numbers should be going down. They are not going down right now.”

DeWine has said the state continues to try to increase its testing capability. Ohio is entering a multi-state purchasing agreement to expand the use of rapid coronavirus tests, DeWine said earlier this week. He said he believes the new tests will allow Ohio to ramp up testing beyond the average of 22,334 tests per day done during the past week.

Cleveland Clinic microbiologist Dan Rhoads said that if the rapid antigen test is being used to insulate the president from exposure to the coronavirus, false positives would alarm the person tested, but wouldn’t interfere with the goal of keeping Trump safe. The antigen test might miss infection in someone who isn’t shedding much virus, but those people aren’t as likely to infect others as those with higher virus levels. Rhoads said each test has its advantages and “you have to take the good with the bad when you do a test.”

“Anybody in lab medicine will tell you that no test is perfect,” said Rhoads. “When the governor gets an imperfect test, everybody realizes that a little more acutely than usual. That’s what happened here.”

Ohio Gov. Mike DeWine acknowledges members of the media while entering his residence after testing positive for COVID-19 earlier in the day Thursday, Aug. 6, 2020, in Bexley, Ohio. DeWine tested positive using a rapid test Thursday, before testing negative later in the day using a more sensitive laboratory-developed test. No test for coronavirus infection is perfect, and test results can be affected by a variety of factors, including the type of test used, the quality of the sample and when it was taken during the course of any infection.
https://www.limaohio.com/wp-content/uploads/sites/54/2020/08/web1_AP20219693719481.jpgOhio Gov. Mike DeWine acknowledges members of the media while entering his residence after testing positive for COVID-19 earlier in the day Thursday, Aug. 6, 2020, in Bexley, Ohio. DeWine tested positive using a rapid test Thursday, before testing negative later in the day using a more sensitive laboratory-developed test. No test for coronavirus infection is perfect, and test results can be affected by a variety of factors, including the type of test used, the quality of the sample and when it was taken during the course of any infection. AP Photo/Jay LaPrete

By Sabrina Eaton

cleveland.com (TNS)

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