For months, the White House’s strategy for keeping President Trump and his inner circle safe has been to screen all White House visitors with a rapid test.
But the product they use, Abbott’s ID Now, was never intended for that purpose and is known to deliver incorrect results. In issuing an emergency use authorization in late March, the Food and Drug Administration said the test was to be used only by a health care provider “within the first seven days of symptoms.”
The ID Now has several qualities in its favor: It’s portable, doesn’t need skilled technicians to operate and delivers results in 15 minutes. Used to evaluate someone with symptoms, the test can quickly and easily diagnose Covid-19, the disease caused by the coronavirus.
In people who are infected but not yet showing symptoms, however, the test is much less accurate, missing as many as one in three cases.
In May, after many reports of problems with the test, the F.D.A. warned that those who test negative using the test should confirm that result with a lab-based test.
Still, the Trump administration has routinely used the test to screen people without symptoms, allowing anyone who tested negative to go without a mask during meetings and official proceedings.
The Rev. John I. Jenkins, the president of the University of Notre Dame, tested positive for the coronavirus after attending the White House announcement of the Supreme Court nominee, Judge Amy Coney Barrett, on Saturday. He apologized for going mask-free at the ceremony but said he had been told he could do so after his rapid test came back with a negative result.
Given the timing of Mr. Trump’s illness, experts said it was quite possible that he was exposed to the virus on that day.