The White House said Biden was suffering from a runny nose, cough and "general malaise.
US President Joe Biden tested positive for Covid on Wednesday, shortly after conceding that he would consider dropping his troubled reelection bid if he was diagnosed with a serious medical condition.
The 81-year-old Democrat gave media the thumbs up from his limousine and said "I feel good" as he cut short a campaign trip to Las Vegas following the diagnosis.
The White House said he was suffering from a runny nose, cough and "general malaise," was taking Covid medication, and was flying straight to isolation at his beach house in Rehoboth, Delaware.
The diagnosis came hours after the release of comments by Biden in an interview conducted on Tuesday, in which he said he could step aside as a presidential candidate "if I had some medical condition that emerged."
It was also the latest development over a dramatic few days in the already frenetic and polarized White House race that saw his rival Donald Trump survive an assassination at a campaign rally of his own.
Biden has been fighting for political survival since a disastrous debate against Trump nearly three weeks ago, in which his tired and confused appearance sparked concerns about his age.
White House Press Secretary Karine Jean-Pierre said Biden had tested positive shortly after the first in a series of events in Las Vegas targeting crucial Latino voters.
"He is vaccinated and boosted and he is experiencing mild symptoms. He will be returning to Delaware where he will self-isolate and will continue to carry out all of his duties fully during that time," Jean-Pierre said.
Biden's doctor said he was suffering from a runny nose and a "non-productive cough" along with "general malaise," the White House said in an accompanying note.
He has received the Covid drug Paxlovid and has already taken his first dose, the statement read.
"His symptoms remain mild, his respiratory rate is normal at 16, his temperature is normal at 97.8 and his pulse oximetry is normal at 97 percent," it added.
- 'I feel good' -
Biden later leaned out of his limousine, dubbed the Beast, as he arrived at a Las Vegas airport to give the thumbs up.
"Good," he said to the press as he walked to Air Force One without a mask. "I feel good."
Janet Murguia, the president of the Unidos union for Latino workers, told the crowd about the diagnosis shortly before the White House announcement.
"I was just on the phone with President Biden, and he shared his deep disappointment at not being able to join us this afternoon," she said.
The furor over Biden's health is now set to go into overdrive, with a growing number of Democrats calling on him to step aside.
Asked what could make him rethink his presidential bid, Biden told the Black media outlet BET in an interview taped Tuesday in Las Vegas: "If I had some medical condition that emerged, if somebody, if the doctors came and said 'you've got this problem, that problem.'"
He suffered a major blow hours earlier on Wednesday when a top Democrat, Representative Adam Schiff of California, urged Biden to "pass the torch."
"A second Trump presidency will undermine the very foundation of our democracy, and I have serious concerns about whether the President can defeat Donald Trump in November," Schiff said in a statement to the Los Angeles Times.
Around 20 House Democrats and one senator have now called on Biden to leave the White House race.
Most polls show Biden trailing the election in a tight race with Trump.
Biden insists that Democratic voters support him, but a poll by the Associated Press and NORC Center for Public Affairs Research said Wednesday that nearly two-thirds want him to step aside.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)