United States President Joe Biden tested positive for COVID-19 again Saturday.

The president's physician, Dr. Kevin O’Connor, said in a letter on Saturday that Biden tested positive for the virus that morning.

The White House physician said that the positive test is believed to be a "rebound" experienced by some COVID patients following treatment with an anti-viral drug.

O'Connor said Biden has experienced no reemergence of symptoms and continues to feel quite well.

Biden had tested positive last Thursday and had been treated with the anti-viral drug Paxlovid.

The U.S. president tweeted on Saturday that he tested positive for COVID-19 in a rebound case, adding he will be working from home for the next couple of days.