▶ Watch Video: President Trump “doing very well,” his physician says

A Saturday press briefing by President Trump’s physician raised many more questions as Dr. Sean Conley told reporters the president was “72 hours into the diagnosis” of COVID-19, indicating the president may have appeared at campaign events in person after he was exhibiting symptoms of the virus. In a memo from the White House, Conley clarified that Mr. Trump was ” first diagnosed with COVID-19 on Thursday, October 1st.” 

While addressing reporters on Saturday morning, Conley refused to say when Mr. Trump had last tested negative for the virus, or how and when he had been infected. If Mr. Trump is 72 hours into his diagnosis, the president may have known he had contracted the virus, or had symptoms, as early as Wednesday. The president met in person with officials in Minnesota on Wednesday and appeared at a fundraiser at his club in Bedminster, New Jersey, on Thursday.

When asked for clarification about the timeline for the president’s diagnosis, Conley said the president’s medical team conducted “repeated testing” on Friday.

“Thursday afternoon, following the news of close contact, is when we repeated testing,” Conley said, adding they received “PCR confirmation” that he was positive for the virus on Thursday evening. The PCR coronavirus test is a molecular test, and it is unclear whether Mr. Trump received a positive diagnosis from a rapid antigen test.

In the memo afterward, Conley said that he had misspoken when he said the president was 72 hours into his diagnosis.

“This morning while summarizing the president’s health, I incorrectly used the term ‘seventy two hours’ instead of ‘day three’ and ‘forty eight hours’ instead of ‘day two’ with regards to his diagnosis and the administration of the polyclonal antibody therapy. The president was first diagnosed with COVID-19 on Thursday, October 1st and received Regeron’s antibody cocktail on Friday, October 2nd,” Conley said, misspelling Regeneron. The memo was not signed.

Conley was also incorrect by calling it polyclonal antibody theory in his memo. “It is two monoclonal antibodies. It was incorrect in the physician’s letter,” Regeneron spokesperson Hala Mirza told CBS News.  

Conley told reporters Mr. Trump was not receiving oxygen treatment on Saturday, but sidestepped questions about whether he had previously been on oxygen. After repeated questioning from reporters, Conley finally said Mr. Trump was not on oxygen on Thursday and had not been treated with oxygen when the president was at Walter Reed on Friday. However, he did not say whether the president had been treated with oxygen on Friday at the White House.

“No oxygen, none at this moment, and yesterday with the team when we were all here, he was not on oxygen,” Conley said, referring to Mr. Trump’s arrival at Walter Reed.

Two sources confirmed to CBS News on Saturday afternoon that Mr. Trump received oxygen at the White House Friday before heading to Walter Reed. However, oxygen treatment is the default for patients in this situation, and it is unclear whether he had trouble breathing and actually needed it.

A White House official told CBS News Conley meant this was the third day of Mr. Trump’s diagnosis, not that he had been diagnosed 72 hours ago. This official said the diagnosis was made Thursday evening, and Mr. Trump had received Regeneron’s polyclonal antibody cocktail later that night. This contradicts Dr. Ben Garibaldi, another member of the president’s medical team, who told reporters the president had received antibody treatment 48 hours ago. The antibody cocktail is still undergoing a clinical trial, and requires approval from the Food and Drug Administration.

Conley also declined to disclose Mr. Trump’s exact temperature when he had a fever, although he said the president had a fever from Thursday into Friday. He told reporters Mr. Trump had not had a fever in 24 hours.

Conley also told reporters Mr. Trump was “doing very well.” This was almost immediately contradicted by a source familiar with the president’s health, who told pool reporters after Conley’s briefing that the president’s vitals were “very concerning.”

“The president’s vitals over the last 24 hours were very concerning and the next 48 hours will be critical in terms of his care. We’re still not on a clear path to a full recovery,” the source said. 

Paula Reid and Kristin Brown contributed to this report.