The Washington PostDemocracy Dies in Darkness

Biden tests positive again for coronavirus after Paxlovid ‘rebound’

The president does not have any symptoms, his physician said, but will reinitiate his isolation

President Biden meets with CEOs in Washington on July 28 after he had tested negative for the coronavirus. (Susan Walsh/AP)

President Biden tested positive for the coronavirus again Saturday, his physician said, after experiencing a Paxlovid “rebound.”

The president’s physician, Kevin O’Connor, said Biden tested negative on Tuesday evening, Wednesday morning, Thursday morning and Friday morning. He tested positive Saturday morning using an antigen test.

Physicians have warned that people who receive the antiviral medication Paxlovid can experience “rebound” infections days after initially testing negative, although data on the frequency of the occurrence and its long-term effects remain unclear.

O’Connor said in a letter that Biden’s symptoms haven’t reemerged, and the president “continues to feel quite well.”

“This being the case, there is no reason to reinitiate treatment at this time, but we will obviously continue close observation,” O’Connor wrote. Biden will go back into isolation at the White House, O’Connor added.

Biden was scheduled to travel to Wilmington, Del., on Sunday and Hemlock, Mich., on Tuesday, but both trips have been canceled, the White House said.

The trip to Michigan was for an event in support of a $52 billion bill to subsidize computer chip manufacturing and research and counter China’s influence, known as the CHIPS and Science Act. The legislation passed both chambers of Congress this week and is awaiting Biden’s signature. It was unclear whether Biden would participate in Tuesday’s event remotely.

Biden was likely infected with the BA.5 variant, O’Connor said last week, an omicron subvariant that has become dominant in the United States and is the most transmissible version of the virus yet. BA.5 has shown a remarkable ability to escape immune protection afforded by vaccines and prior coronavirus infection.

Biden emerged from his five-day isolation Wednesday and delivered a speech from the Rose Garden about how his mild covid infection was a reflection of the administration’s pandemic response and the tools it had made widely available, including antivirals, at-home tests and boosters.

He conducted a series of public events this week in support of the CHIPS bill and on the economy. Biden did not hold any public events Friday.

While it’s possible that Biden could have been shedding virus during the days he tested negative, it’s unlikely he would have been able to transmit the virus given his negative antigen tests, said Abraar Karan, an infectious-disease physician and researcher at Stanford University.

Biden removed his mask for some of the events. White House press secretary Karine Jean-Pierre said Biden was still in compliance with guidelines from the Centers for Disease Control and Prevention because he was more than six feet apart from others.

CDC guidance recommends people isolate for five days after testing positive for coronavirus and wear a mask for an additional five days when around others. Some experts have said the guidance could cause people to return to work or leave isolation when they are potentially still infectious.

Besides Biden, notable figures who experienced rebound infections include 81-year-old Anthony S. Fauci, the president’s chief medical adviser, who contracted the coronavirus earlier this summer. The rebound infection can also lead to further complications, as with the initial infection, but many people describe their symptoms as mild.

Paxlovid, which is taken in a five-day course, suppresses the amount of virus in a person’s system while the treatment is being taken. Some experts theorize that the rebound infections occur because the five-day course is too short and should be lengthened by several days, to ensure that the virus has been eradicated.

The CDC in late May noted that patients can test positive again after completing the five-day course of Paxlovid and advised such people to go into isolation again for at least five days.

Experts are divided on whether patients should begin another course of Paxlovid if they rebound. Fauci later disclosed that he took a second course of Paxlovid after getting a rebound infection.

Biden addressed his rebound case on Twitter on Saturday but reassured people he was continuing to work and would resume traveling soon.

“Folks, today I tested positive for COVID again. This happens with a small minority of folks,” Biden wrote on Twitter. “I’ve got no symptoms but I am going to isolate for the safety of everyone around me. I’m still at work, and will be back on the road soon.”

Dan Diamond contributed to this report.