President Joe Biden tested positive for COVID-19 again on Saturday morning, the president's physician said.
Dr. Kevin O'Connor, the White House physician, said in a letter that it's a rare "rebound" case usually observed in a small percentage of patients treated with Paxlovid.
Biden has experienced no reemergence of symptoms and "continues to feel quite well," O'Connor said in the letter.
Paxlovid and 'Rebound' COVID-19Paxlovid is recommended by the Centers for Disease Control and Prevention (CDC) for early-stage treatment of mild to moderate COVID-19 among high-risk patients.
"COVID-19 rebound has been reported to occur between two and eight days after initial recovery and is characterized by a recurrence of COVID-19 symptoms or a new positive viral test after having tested negative," CDC said in a health advisory in May.
No evidence shows that additional treatment is needed in the so-called COVID-19 rebound cases.
Researchers from the University of California–San Diego School of Medicine said the rebound may be caused by insufficient exposure to the drug.
Breach of CDC ProtocolsWord of Biden’s positive test came just two hours after the White House announced a presidential visit to Michigan this coming Tuesday to highlight the passage of a bill to promote domestic high-tech manufacturing. Biden had also been scheduled to visit his home in Wilmington, Delaware, on Sunday morning, where First Lady Jill Biden has been staying while the president was positive.
Both trips have been canceled as Biden has returned to isolation.
Biden, 79, was treated with the anti-viral drug Paxlovid and tested negative for the virus on Tuesday and Wednesday. He was then cleared to leave isolation while wearing a mask indoors. His positive test put him among the minority of those prescribed the drug to experience a rebound case of the virus.
While Biden was testing negative, he returned to holding in-person indoor events and meetings with staff at the White House and was wearing a mask, in accordance with CDC guidelines.
But the president removed his mask indoors when delivering remarks on Thursday and during a meeting with CEOs in the White House complex.