MMH: ‘Increasing concern’ some negative results are false negatives

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According to the WHO, there has been no evidence to date to suggest the virus could be transmitted by mosquitoes. Photo: Andre Penner, STF / AP Photo: Andre Penner, STF / AP Image 1 of / 24 Caption Close MMH: ‘Increasing concern’ some negative results are false negatives 1 / 24 Back to Gallery

Midland hospital officials believe some of the negative COVID-19 results they’ve received are false negatives, and they are becoming increasingly concerned about that possibility, Dr. Larry Wilson said Friday.

Wilson, Midland Memorial Hospital’s medical chief of staff, said in an interview that the hospital’s infectious disease and critical care doctors believe a percentage of the 64 patients who tested negative are infected with COVID-19.

“If you look at the Seattle data and elsewhere, they had about a 7 percent positivity rate on their COVID tests, which suggests that many people that are sick and infected aren’t coming up positive on this test,” he said. “So, we’re having increasing concern that there may not be a super sensitive test. It may not be helping us as much as we think it can.”

He said several patients admitted to the hospital have had symptoms and laboratory findings consistent with the novel coronavirus but have tested negative.

“[They] have the characteristic lung appearance of the COVID-19 infection, they behave like the COVID-19 infection … they test negative for all the other normal viruses that might cause lung infections and their COVID test is negative as well,” Wilson said. “The concern is that they probably have COVID but somehow we’re catching them at a time when they’re not shedding the virus.

“It’s a little too coincidental that we know we have it in the community, we’ve seen these patients in a larger number than we would normally see them and we don’t really have a good explanation for why they’re behaving this way without attributing it to this new infection.”

It is possible that patients are falsely testing negative for other respiratory infections, such as the flu, Wilson said. He said data from China and other countries suggests the COVID-19 test has a sensitivity rate of 75 percent, meaning it is not accurately detecting the virus in 25 percent of cases.

The hospital is combatting the possibility of false negatives by treating every patient who presents with symptoms as if they have the coronavirus, Wilson said.

“If they look like it, behave like it, [we] treat them like it and treat them all the way through” their illness, he said. He said the patients who have tested negative have still been advised to self-quarantine until at least 72 hours after their symptoms resolve.

“Anybody who’s got a respiratory tract illness today, they should stay home,” Wilson said.

MMH officials are considering retesting patients who return negative results, but likely will not retest patients tested last week, according to Wilson. He said the virus is detectable in most people between 12 to 24 hours before they develop a fever and a few days after symptoms begin.

Patients who have received treatment and are seeing an improvement in their symptoms have a small likelihood of testing positive for the virus, even if they have been infected with it, Wilson said.

He said hospital staff might retest patients with acute symptoms going forward, when rapid response tests are available, and patients could be retested more quickly.