When Maree Johnson-Baruch and her family fell ill with symptoms of Covid-19, they thought tests would confirm the infections. But months later, multiple rounds of testing have produced conflicting results—highlighting the unreliability of existing tests for the new coronavirus, Reuters' Jonathan Allen reports.

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Are Covid-19 tests unreliable?

In light of the new coronavirus' spread throughout the United States, the country has seen growing demand for diagnostic tests for Covid-19, the disease caused by the virus, as well as for tests to determine whether Americans have developed antibodies for the virus—which could indicate they previously were infected and therefore might have some immunity to the virus.

To address the increasing demand and expand testing capacity in the United States, FDA in March relaxed regulations that ordinarily would require manufacturers to receive the agency's approval before distributing the tests (though FDA recently enacted new standards for antibody tests for the new coronavirus). The initial move allowed labs to start using the tests without them first undergoing a formal review to determine whether they're effective.

However, Bill Miller, a physician and epidemiologist at Ohio State University, said the relaxed requirements mean "[t]he whole testing field is in flux." He explained that a majority of the tests are "going through a really rapid validation process" instead of the more-thorough process that's usually required for approval, and "[a]s a result, we can't be completely confident in how they will perform."

Overall, health care experts estimate that about one-third of patients who are infected with the novel coronavirus and who are tested for it receive negative test results, meaning some people could be exposing others to the virus unknowingly.

Further, experts say early data suggests many of coronavirus antibody tests are unreliable.

One household, many different test results

According to Allen, the Baruch family's experience with testing for the new coronavirus reflects the undependability of the tests currently available in the United States.

When the Baruch family fell ill around the same time with similar symptoms of Covid-19, they were convinced they had contracted the new coronavirus. Maree Johnson-Baruch on March 12 was the first to experience mild symptoms like subtle muscle aches. The following Monday she developed a fever and soon realized she had lost her sense of smell. Over the next week, Maree's husband, Jason Baruch, and her two daughters also fell ill.

The Baruch family called the New York State Department of Health's coronavirus hotline for advice, but due to a scarcity of testing kits, the family was unable to get tested for the new coronavirus. The family stayed at home until they no longer were experiencing symptoms.

In April, after they recovered from the illness, Maree heard of an experimental therapy at Mount Sinai Hospital using the blood plasma of patients who had recovered from Covid-19 to help treat people currently hospitalized with the disease. Believing they were previously infected with the new coronavirus, Maree and her husband went to the hospital to get tested for antibodies.

"The strange thing was I tested positive and Jason tested negative," Maree said.

Ania Wajnberg, who oversees antibody testing at Mount Sinai, said the results were not altogether surprising. According to Wajnberg, the hospital's antibody test failed to detect antibodies in about 6% of patients.

"I get tons of questions about what the results mean, and we don't know exactly what they mean," Wajnberg said.

Over a month after Maree had contacted the state's health department, an official called and told the family that they qualified for a test that could detect whether RNA from the new coronavirus was present in their bodies. The entire family received the tests, but again they got confusing results: While Maree, Jason, and their youngest daughter tested positive for the virus, their eldest daughter tested negative.

Maree and Jason's eldest daughter was tested for antibodies for the virus once more at a walk-in clinic, and this time tested positive. Jason is seeking another test since his first two came back with conflicting results, Allen reports.

"No one's really willing to put themselves on the line and say, 'Hey, you're home free, you have antibodies,' or, 'You're still contagious,'" Jason said. "No one really wants to tell us—definitively—anything."

But it's possible the Baruch family might not be able to get the definitive answers they're seeking at this time.

Danielle Ompad, an epidemiologist at New York University's School of Global Public Health, said, "People are way more comfortable with 'yes' or 'no' than 'maybe,'" but "[u]nfortunately, that's where the science has us right now: we just don't know, and it's much better to say that we don't know than to try to make predictions without having the data there because that can be detrimental" (Allen, Reuters, 5/7).