Adm. Brett P. Giroir, the administration’s coronavirus testing czar, called it a “C.D.C. action,” written with input from the agency’s director, Dr. Robert R. Redfield. But he acknowledged that the revision came after a vigorous debate among members of the White House coronavirus task force — including its newest member, Dr. Scott W. Atlas, a frequent Fox News guest and a special adviser to President Trump.

“We all signed off on it, the docs, before it ever got to a place where the political leadership would have, you know, even seen it, and this document was approved by the task force by consensus,” Dr. Giroir said. “There was no weight on the scales by the president or the vice president or Secretary Azar,” he added, referring to Alex M. Azar II, the secretary of health and human services…

In a brief interview, Dr. Fauci said he had seen an early iteration of the guidelines and did not object. But the final debate over the revisions took place at a task force meeting on Thursday, when Dr. Fauci was having surgery under general anesthesia to remove a polyp on his vocal cord. In retrospect, he said, he now had “some concerns” about advising people against getting tested, because the virus could be spread through asymptomatic contact.

“My concern is that it will be misinterpreted,” Dr. Fauci said.