President Joe Biden has tested positive again for Covid-19, the White House said on Saturday. His physician, Dr Kevin O'Connor, said he's not experiencing any symptoms, but that he will isolate at the White House.

Notably, Biden tested positive for the virus again almost three days after exiting coronavirus isolation.

According to the doctor, it is a rare case of "rebound".Biden will reenter isolation for at least five days. He experienced no reemergence of symptoms and continued to feel quite well. Earlier, O’Connor had warned of the potential for a “rebound”.

It is a Covid positivity observed in a small percentage of patients treated with PAXLOVID. In a memo, O'Connor said, "The President had increased his testing cadence, both to protect people around him and to assure early detection of any return of viral replication."As per the physician, there is no reason to reinitiate treatment at this time, but we will obviously continue close observation.

"However, given his positive antigen test, he will reinitiate strict isolation procedures. As I’ve stated previously, 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," O’Connor wrote in the memo.Notably, Biden tested negative for Covid-19 on Tuesday, Wednesday, Thursday and Friday. On July 21, the US President tested positive for the virus. He then went into isolation.

On Wednesday, he emerged out of the Covid-19 isolation. He was reportedly infected by BA.5 variant. It was noted that one to two percent of people who participated in Pfizer's original study on Paxlovid experienced virus rebound after 10 days. Paxlovid is an antiviral drug used to treat Covid-19.