Washington (Reuters) – U.S. President Joe Biden tested positive for COVID-19 again on Saturday morning in what the White House doctor describes as a “rebound” case seen in a small percentage of patients who take the antiviral drug Paxlovid.
Biden, 79, who emerged from COVID isolation on Wednesday after testing positive on July 21, will now return to strict isolation and will cancel planned trips to his home in Wilmington and work trip in Michigan, the White House said. Biden held public events on Wednesday and Thursday, but none on Friday.
Biden had planned the Michigan trip to tout Thursday’s passage of legislation to boost the semiconductor chips industry, which the White House announced earlier Saturday.
Biden’s positive test is believed to be “rebound” positivity experienced by some COVID patients who take the anti-viral drug Paxlovid, according to White House physician Dr. Kevin O’Connor. Paxlovid is an antiviral medication from Pfizer Inc (PFE.N) that is used to treat high-risk patients, such as older patients.
A small but significant percentage of people who take Paxlovid will suffer a relapse or a rebound that occurs days after the five-day treatment course has ended, studies have shown.
Biden tweeted about his positive case, saying it can happen to a “small minority of folks.”
“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,” he tweeted.
O’Connor said Biden, who is 79, tested negative for the last four days, and there is no plan to reinitiate treatment given his lack of symptoms.
Biden previously described his experience with COVID as mild, saying he was able to continue working while in isolation and attributed his relative ease with the disease to vaccines and other treatments.
O’Connor had previously said Biden would be tested regularly to watch for a potential “rebound” COVID-19 case, which can be experienced by some patients who have been treated with Paxlovid, the drug the president received.