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Testing Negative for COVID-19 May Not Mean You Don’t Have The Disease

A health care worker prepares to administer a nasal swab for a COVID-19 drive-by testing site
Marta Hart, medical assistant and X-ray technician, administers a COVID-19 test outside of the facility at the Urgent Care Center of Connecticut in Bloomfield on March 25, 2020.

The shortage of coronavirus tests remains a problem nationwide. And while a positive test result means it’s almost certain that a person is infected, many doctors are expressing concern about sick patients who test negative. We depend on your support. 

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More and more stories are surfacing about patients presenting typical COVID-19 symptoms but getting negative test results. Some doctors have even seen hospitalized patients testing negative. And how do you explain two people exhibiting the same symptoms with one testing positive and the other negative?

“It’s always important to take a look at the big picture — the way you feel, the exposures you've had, the moment in history where such a virus is spreading,” said Dr. Harlan Krumholz, professor of medicine at Yale and director of the Yale New Haven Hospital Center for Outcomes Research and Evaluation. "If you're in the midst of that and you're developing symptoms, which are typical of the pandemic, then one piece of information — the test itself — shouldn't necessarily quash everything else."

Krumholz said that while diagnostic tests in general aren't always perfect, he and others are discovering that false negatives in COVID-19 tests seem uncomfortably common.

“A study out of China looked at a bunch of people who felt sick in ways that were very consistent with COVID-19 — not only were they from Wuhan where the pandemic hot spot began, but their X-ray findings were very consistent with the disease,” Krumholz said. “It was almost certain that these people had it. They met all the criteria, and yet the tests were negative in about 30 percent of the cases.”

Some doctors have expressed concern that the false-negative rate in the U.S. could be even higher than 30 percent. Krumholz said they really don’t know how good the tests are in this fast-changing environment. In addition, other issues can factor into false-negatives, including substances used in the tests and inadequate sample collections.

“In actual practice, in the way in which we’re collecting the information, especially in this massive ramp-up, lots of different people are now collecting the samples, people who may not have been used to doing that before,” said Kromholz. “Manufacturers had to ramp up the kits really fast. In addition, it becomes a bit difficult to know, because you need a gold standard, so how can you tell if someone actually is infected if the test is negative?”

If you’ve likely been exposed to COVID-19 or have symptoms, Krumholz said it's best to assume you have the infection, even if you test negative. A negative test does not mean that a person is not infectious.

“You need to be staying away from people,” Krumholz said. “That’s good advice for everyone. And we’re beginning to take that on as we’re social-distancing and sheltering and talking about masks in public.”

Krumholz is hopeful that there are better tests around the corner that will reveal more information about the illness .

“These tests are going to look at antibodies to see whether we’ve mounted resistance to the virus,” he explained. “Have we fought it and won? Many people out in the community who didn’t really know they were sick or had minor symptoms — are they people who were infected and got through it? That would be helpful to us. And then another question that’s looming is whether that information could tell you who might be safe.”

In the meantime, Krumholz said doctors are focusing more on how much weight they should place on specific pieces of evidence, and using all sources of information available for a better sense of the bigger picture.

Lori Connecticut Public's Morning Edition host.

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