A new study measuring the performance of Abbott’s rapid, point-of-care coronavirus test found the device could miss nearly half of positive cases, depending on how the samples were handled and fed into the machine.
Conducted by researchers at NYU Langone Health, involving 101 patients receiving emergency COVID-19 care through the system’s Tisch Hospital, the study was pre-published on bioRxiv, and has not yet been peer-reviewed.
Each patient had samples collected twice at the same time—once using a dry nasal swab, and once with a longer swab reaching deeper into the nose that was then submerged in viral transport media. All samples were taken to the hospital’s laboratory within one or two hours, and tested using Abbott’s ID NOW analyzer and Cepheid’s Xpert Xpress test.
Both are small, countertop devices designed to produce results in minutes or less than an hour. Abbott’s test has been touted by the White House, and regularly used to screen those who may come in contact with the president or the administration’s staff. Cepheid’s device was the first point-of-care system authorized by the FDA in late March, followed days later by the ID NOW test.
Among the dry nasal swab samples that returned a positive result with Cepheid’s test, about 48% falsely read as negative when run through Abbott’s ID NOW.
Across both the dry and submerged sample collection and transport methods, the ID NOW test missed one-third of the samples detected positive by Xpert Xpress, according to NYU researchers.
Abbott has said that the best method for getting accurate results from its test is to use the device as close as possible to the patient, and has told users to insert dry swabs directly into the machine with little delay after samples are taken.
The company said that the use of viral transport media to store swabs for a period of time could end up diluting the sample in the liquid solution, ultimately reducing the sensitivity of the test. Previously Abbott reported a 0.02% rate of false negatives, and in statements has said that it is unclear whether the samples were correctly tested in the study.
According to a recent update, the company has shipped 1.7 million ID NOW tests nationwide, with the majority focused on COVID-19 outbreak hot spots and priorities given to healthcare workers and first responders. Abbott said it is currently manufacturing 50,000 tests per day, with plans to increase capacity up to 2 million tests per month by the end of June.
In a statement, the FDA said it is evaluating reports of inaccurate results and that it is in direct communication with Abbott—and that, in the meantime, negative results may need to be confirmed with a separate molecular test.
“We will continue to study the data available and are working with the company to create additional mechanisms for studying the test,” said Tim Stenzel, director of the agency’s Office of In Vitro Diagnostics and Radiological Health. “This test can still be used and can correctly identify many positive cases in minutes.”
The agency said it has received 15 adverse event reports about the ID NOW test related to inaccurate results, but added that no diagnostic test “will be 100% accurate due to performance characteristics, specimen handling or user error.”
Abbott, meanwhile, has agreed to conduct postmarket studies evaluating the device in a variety of clinical settings.
Editor's note: This story has been updated with the FDA's statement.