U.S. President Joe Biden continued to test positive for COVID-19 on Tuesday and will maintain his isolation procedures, but he is feeling well and does not have a fever, his physician said in a memo released by the White House.

"The President continues to feel well, though he is experiencing a bit of a return of a loose cough," his physician Kevin O'Connor said. "He remains fever-free and in good spirits."

Biden, 79, had just emerged from isolation on Wednesday last week after testing positive for COVID for the first time on July 21. He tested positive again on Saturday in what O'Connor described as a "rebound" case seen in a small percentage of patients who take the antiviral drug Paxlovid.

Paxlovid is an antiviral medication from Pfizer Inc that is used to treat high-risk patients, such as older patients.

The White House said on Monday that Biden was feeling fine and looking forward to getting back on the road.