Nevada has suspended the use of two rapid COVID-19 tests in nursing homes after the tests repeatedly delivered false-positives, according to an Oct. 2 directive issued by the state health department.
Some test results from Quidel or Becton, Dickinson and Co. mistakenly designated healthy individuals as infected, prompting a statewide order to discontinue use "until the accuracy of the tests can be further evaluated." The state is now pivoting from antigen tests to viral RNA tests.
In August, the federal government distributed the antigen tests, which can produce results in 15 minutes, to nursing homes across the U.S.
In their applications for FDA clearance, both BD and Quidel said their tests had no false positives, according to The New York Times. However, as the creators of the test, BD and Quidel are more likely to use it correctly, said Valerie Fitzhugh, MD, a pathologist at New Brunswick, N.J.-based Rutgers University.
Shortly after the tests were distributed, Nevada nursing homes began to report conflicting results between some rapid tests and PCR lab results. Of 39 positive test results from both BD and Quidel, 23 were found by PCR to be negative, an error rate of almost 60 percent, reports the NYT.
The situation in Nevada doesn't necessarily represent the performance of the antigen tests in other contexts. Both tests received FDA approval only for use "within the first five days of the onset of symptoms." Susan Butler-Wu, PhD, a clinical microbiologist at Los Angeles-based University of Southern California, said Nevada's data could be due to the off-label use of tests designed for certain populations but then administered to others.
Douglas Bryant, president and CEO of Quidel, told reporters it was "highly likely" the PCR tests used to confirm the test results were erroneous. Jeannine Sharp Mason, Quidel's director of marketing communications, told the NYT the company was aware of the situation and remained "confident in the accuracy of our rapid antigen tests."
Kristen Cardillo, BD's vice president of global communication, said the company was "conducting thorough investigations," but that the company believes the rate of reported false positives is well within what is expected.