Navy commander Dr Sean Conley said Mr Trump has been fever-free for 24 hours as he updated the nation on the president’s condition from the hospital on Saturday morning local time.
Mr Trump was admitted to Walter Reed National Military Medical Centre on Friday afternoon in what doctors say was a precaution after he and First Lady Melania Trump tested positive for Covid-19.
He has not transferred powers.
While Dr Conley said the president is not currently on oxygen, he refused to say whether the president had ever been on oxygen, despite repeated questioning.
He said that Mr Trump’s symptoms, including a cough and nasal congestion, “are now resolving and improving”.
“He’s in exceptionally good spirits,” said another doctor, Sean Dooley.
Dr Conley said the president has “a lot of work to do” and is doing it.
Doctors say the president told them: “I feel like I could walk out of here today.”
However, a person familiar with Mr Trump’s Covid-19 illness told the Associated Press some of his vital signs over the past 24 hours were “very concerning” but they have improved since he was admitted to hospital.
The person, who has knowledge of the president’s medical condition, described the next 48 hours as critical and said there was no clear path yet on a recovery and that it could be days before he was discharged.
The decision to have Dr Conley brief reporters marked a change in strategy for an administration that has so far been less than transparent about the virus’s spread inside the White House.
It was Bloomberg News – not the White House – that broke the first news that a close aide to Mr Trump had been infected.
And aides had declined to share basic health information about the president, including a full accounting of his symptoms, what tests he has undertaken and the results.
In a memo released shortly before midnight, Dr Conley did report that Mr Trump had been treated at the hospital with remdesivir, an antiviral medication that has been promoted by many in the administration, after taking another experimental drug at the White House.
He added that Mr Trump was “doing very well” and is “not requiring any supplemental oxygen”.
The White House said Mr Trump was expected to stay at the hospital for “a few days” and he would continue to work from the hospital’s presidential suite, which is equipped to allow him to keep up his official duties.
In addition to accessibility to tests and equipment, the decision was made, at least in part, with the understanding that moving him later, if he took a turn for the worse, could send a worrying signal.
As the White House works to piece together the flurry of new infections, attention is focused in particular on last Saturday’s White House event introducing Mr Trump’s Supreme Court nominee.
That day, Mr Trump gathered more than 150 people in the Rose Garden, where people mingled, hugged and shook hands – overwhelmingly without masks.
There were also several indoor receptions, where Mr Trump’s Supreme Court pick, Judge Amy Coney Barrett, her family, senators and others mingling in the close quarters of the White House, photographs show.
Among those who attended who have now tested positive are former White House counsellor Kellyanne Conway, the president of the University of Notre Dame, and at least two Republican legislators – Utah Senator Mike Lee and North Carolina Senator Thom Tillis.
The decision for the president to leave the White House for the hospital capped a day of drama in Washington on Friday.
The president, who has spent months playing down the threat of the virus, was forced to cancel all campaign events a month before the election as he fought a virus that has killed more than 205,000 Americans and is hitting others in his orbit as well.
Mr Trump walked out of the White House on Friday evening wearing a mask and gave a thumbs-up to reporters but did not speak before boarding Marine One.
Members of the aircrew, Secret Service agents and White House staff wore face coverings to protect themselves from the president onboard the helicopter.
In a video taped before leaving for Walter Reed, Mr Trump said: “I think I’m doing very well, but we’re going to make sure that things work out.”
“Going well, I think! Thank you to all. LOVE!!!” he wrote in his first tweet from the hospital on Friday night.
