Abbott said the researchers didn’t use the test as intended and that the false-negative rate, as reported to the company, is 0.02%.

Shares of the company fell 1.6% to $92.35 at 1:28 p.m. in New York. They are up 6.4% this year.

The White House is frequently testing staff, governors, lawmakers, reporters and others who come in close contact with the president using ID Now. The testing machine, which is roughly the size of a toaster, is portable and doesn’t require deep nasal swabs, about which President Donald Trump once said there is “nothing pleasant.”

Trump touted the Abbott machine with great fanfare in the White House Rose Garden after the Food and Drug Administration approved it for emergency use, saying it could be a godsend for hospitals and workplaces because it “delivers lightning-fast results in as little as five minutes.”

“That’s a whole new ballgame,” the president said at the March 30 event.

The results of the NYU study, if confirmed, indicate the test may still suffer from high false-negative rates despite changes recommended by the company to avoid such a problem. In April, after other academic researchers raised concerns about the issue, Abbott told clinicians to avoid storing samples in so-called transport media, a liquid used to hold the sample, as that might dilute the test and lead to false negatives.

But when the NYU authors attempted to account for changes and avoid false negatives by using dry swabs, the performance was even worse. It missed the virus in 48% of the samples that were positive using Cepheid GeneXpert, a standard reference test sold by Danaher Corp. The NYU study hasn’t yet been reviewed by outside experts or published in a scientific journal.

Abbott said its scientists are still reviewing the 12-page paper. It has distributed about 1.8 million ID NOW tests and said it hasn’t found the problem identified by the NYU report.

“It’s unclear if the samples were tested correctly, and we’re further evaluating the results,” said Darcy Ross, an Abbott spokeswoman. “The test is performing as expected when it’s used correctly.”

On-site test

Abbott’s ID NOW is a point-of-care test that can be done quickly in a health-care setting. Other tests require a sample to be shipped to a lab, with results available after several days. The rapid approach has been widely viewed as a key to ramping up hamstrung U.S. testing efforts, giving answers more efficiently and directing resources to those who are truly sick.

Concerns about false negatives, though, call into question whether the Abbott test will be able to alleviate the strain on U.S. testing efforts as intended.

Scientists have developed a variety of tests to detect the novel coronavirus,
and some haven’t been vetted with the usual rigor by federal health regulators. It is also still unclear at what point in the incubation period of the virus any test is most likely to produce an accurate result. Enough information about the virus is simply not yet known.

Several tests have sparked concern about false negatives. Doctors have reported patients with obvious signs of the disease testing negative. While the scale of the problem hasn’t yet been determined, experts agree that it is prevalent.

False negatives can hinder diagnosis of disease, obscure the full scope of an outbreak and raise the potential that sick people could unknowingly spread a pathogen.

Doctors at hospitals around the country have reported patients testing negative sometimes multiple times before eventually testing positive. Some doctors have instead at times turned to other methods of diagnosis, such as chest X-rays or CT scans.