▶ Watch Video: Latest on President Biden’s rebound COVID case

Washington — President Biden tested positive for COVID-19 again Monday, according to the White House physician, as he continues to experience a rebound infection that can occur in patients taking the Paxlovid antiviral treatment.

Dr. Kevin O’Connor, Mr. Biden’s physician, said in a letter distributed by the White House that the president “continues to feel well as he starts his week.” Mr. Biden’s positive COVID-19 antigen test, taken Monday morning, was “anticipated,” he added.

O’Connor said the president will continue strict isolation measures and work from the Executive Residence at the White House.

“The president continues to be very specifically conscientious to protect any of the Executive Residence, White House, Secret Service and other staff whose duties require any (albeit socially distanced) proximity to him,” he wrote.

Mr. Biden first tested positive for COVID-19 on July 21 and experienced mild symptoms. He began taking Paxlovid, the antiviral drug developed by Pfizer, and completed a five-day course one week ago. The president then received two negative test results — first Tuesday evening and again Wednesday morning — and ended his isolation, delivering remarks in the Rose Garden at the White House to mark the progress made in the treatments available for those who contract the coronavirus.

But Mr. Biden revealed Saturday that he tested positive again, but did not have any symptoms. “Rebound positivity” occurs in a small percentage of patients who take Paxlovid.