President Joe Biden again tested positive for COVID-19 on Monday but “continues to feel well,” his doctor said.

Biden was released from his first round of isolation after testing negative for COVID-19 last Tuesday and Wednesday. However, he tested positive again on Saturday in what White House physician Kevin O’Conner described as a “rebound” case seen in a small number of people who take the anti-viral drug Paxlovid.

O’Conner has said the president will continue the strict isolation measures and is continuing to be careful around White House staff, the Secret Service, and any other people who are in any sort of proximity to him.

Biden “will continue to conduct the business of the American people from the Executive Residence,” for the rest of his time in isolation, O’Conner said.

The president posted a video Saturday from a White House balcony with his dog, Commander. “I’m feeling fine, everything is good, but Commander and I got a little work to do,” he said.

Biden is fully vaccinated and has two booster shots, all of them Pfizer/BioNTech COVID-19 vaccine.