President Joe Biden has continued to test positive for Covid-19, his White House doctor said Tuesday, and is experiencing a return of at least one symptom, described as a "loose cough."

After previously suggesting that Biden was symptom free since coming down with a "rebound" case of Covid, White House physician Kevin O'Connor said "the president continues to feel well, though he is experiencing a bit of a return of a loose cough."

Biden remains "fever free and in good spirits," O'Connor said in his daily memorandum.

"His temperature, pulse, blood pressure, respiratory rate and oxygen saturation remain entirely normal. His lungs are clear," he added.

Biden, who at 79 is the oldest person to hold the presidency, continues to self-isolate after once again testing positive.

Biden had recovered last week from a first bout of Covid, but after four days of negative tests he again had a positive result Saturday.

In a memorandum Sunday, O'Connor linked that result to "rebound positivity."

He said patients treated with Paxlovid -- as Biden was -- sometimes clear the virus but still test positive afterward.