President Joe Biden is back in isolation and has tested positive for COVID-19 for the second day in a row, as he experiences what is known as rebound after taking Paxlovid to treat his original infection.

Biden, who had left isolation three days prior after testing negative, returned to the safety measure on Saturday after testing positive. He tested positive again on Sunday.

Despite the test results, the president “has experienced no reemergence of symptoms and continues to feel quite well,” White House physician Dr. Kevin O’Connor said in a letter released on Sunday describing Biden’s condition. “There is no reason to reinitiate treatment at this time.”

The president had previously isolated for five days and will do so again at the White House for at least five days and a negative test, in accordance with guidelines from the U.S. Centers for Disease Control and Prevention.

Most rebound cases are mild, according to the CDC.

Estimates about how common rebound cases are after taking antiviral drug Paxlovid vary.

Data “suggests that between 5 and 8% of people have rebound,” Dr. Ashish Jha, the White House COVID-19 coordinator, said last week, the AP reported. Dr. Anthony Fauci, the nation’s leading infectious diseases doctor, experienced COVID rebound recently.

Patients with rebound COVID should isolate for at least five days, stopping once fever has resolved for 24 hours without medication and symptoms have improved, the CDC advises. Patients should wear a mask for 10 days after rebound symptoms begin. Some people will test positive after that but are less likely to shed virus.

Despite the rebound cases, Paxlovid has been found to reduce severe disease and death in vulnerable patients. Biden is 79.

He was treated with Paxlovid after first testing positive on July 21. Biden had tested negative last Tuesday and Wednesday, allowing him to leave isolation.

“Acknowledging the potential for so-called rebound COVID positivity observed in a small percentage of patients treated with Paxlovid, the President increased his testing cadence, to protect people around him and to assure early detection of any return of viral replication,” O’Connor wrote last week.

Biden had continued to test negative on Thursday and Friday mornings before he tested positive on Saturday morning.

“This in fact represents ‘rebound’ positivity,” O’Connor wrote Saturday.

While Biden had two initial doses of the Pfizer vaccine before taking office in January 2017, as well as booster shots in September 2021 and March 2022, the BA.5 subvariant has been even more “immune-evasive” than its predecessors, Jha said.

“We have seen lots of people get reinfected within 90 days,” Jha said, though public health officials are still gathering data on that, the AP reported.

Biden has continued to work during his isolation, tweeting a photo of himself signing a declaration for individual assistance for Kentucky playdate survivors and a short video with his dog, Commander, on the White House balcony after his rebound infection.

“I’m feeling fine, everything is good,” Biden said. “But Commander and I got a little work to do.”

Biden had been scheduled to travel Sunday to Delaware, where First Lady Jill Biden has been staying during her husband’s COVID isolation, and fly to Michigan on Tuesday to promote domestic high-tech manufacturing, but both trips had to be canceled, the AP reported.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

SOURCE: Associated Press

Source: HealthDay