In raising the testing issue, the president appeared to refer to a practice that limited the ability of laboratories run by states, universities and private companies to conduct medical screenings not approved by the Food and Drug Administration.
On Saturday, the agency’s commissioner, Stephen M. Hahn, allowed those labs to use tests that they had independently developed. The labs had to submit evidence of the tests’ accuracy before the F.D.A. completes its review. Dozens of labs have now applied for emergency approval under the decision.
Dr. Robert Redfield, the C.D.C. director, said the change was quickly making tests more available. “It’s really very important,” he said at the White House event with Mr. Trump. “It’s what’s changed the availability of testing overnight.”
Michelle Forman, a spokeswoman for the Association of Public Health Laboratories, whose members had complained that the Food and Drug Administration took too long to approve their tests, said there were some discussions during the Obama administration about whether to tighten restrictions on laboratories that developed their own tests, but “nothing was ever put into place.”
She said the association, which represents state and local government labs, was not aware of any Obama-era rules that changed how the labs were regulated or how applications in a public health crisis were reviewed.
Dr. Luciana Borio, who oversaw public health preparedness for the National Security Council in Mr. Trump’s White House and was previously the acting chief scientist at the Food and Drug Administration under Mr. Obama, also said she was unaware of any such rule changes during the last administration.
The F.D.A. had long held that in an emergency, it wanted to ensure that labs develop tests that were accurate, she said. But “it shouldn’t be more onerous, in theory, because these are very speedy and streamlined,” she said, adding that such approvals can happen within 24 hours.