Epidemiologist explains ‘rebound COVID’ after President Biden tests positive again

Biden returns to isolation after being cleared for just over 3 days

Epidemiologist Dr. Jonathan Kantor joins us to discuss the case of "rebound COVID" which seems to be affecting President Biden and others, and whether the anti-viral drug Paxlovid is effective at treating this.

After President Joe Biden tested positive for COVID-19 again Saturday, slightly more than three days after he was cleared to exit coronavirus isolation, local epidemiologist Dr. Jonathan Kantor with the Penn Center for Global Health explained that “rebound COVID” is not that different from other illnesses where a patient may start to feel better and then get sick again.

“With COVID, you can actually be in a situation where it clears so that you’re testing actually as negative,” Kantor said. But then what happens is a few days later, sometimes even longer, they start to get a little symptomatic again, some people don’t get symptomatic, but they do test positive again. So that’s what we mean by rebound. It’s sort of just the idea that you had COVID, you seemed to resolve, but then it’s manifesting again whether clinically or on the basis of testing.”

White House physician Dr. Kevin O’Connor said in a letter that Biden “has experienced no reemergence of symptoms, and continues to feel quite well.” O’Connor said “there is no reason to reinitiate treatment at this time.”

Biden had been treated with an anti-viral drug during his earlier bout with COVID.

In accordance with Centers for Disease Control and Prevention guidelines, Biden will reenter isolation for at least five days. He will isolate at the White House until he tests negative. The agency says most rebound cases remain mild and that severe disease during that period has not been reported.

Kantor said because the president isn’t experiencing symptoms, it’s likely someone in a similar situation who isn’t tested on a regular basis like the president wouldn’t even have realized they were positive for COVID again.

“That’s why a lot of the prominent people we’re seeing, like Dr. Fauci, for example, President Biden, you know, these are people who are tested very aggressively, who are very sensitive to their symptoms. So, of course, they are going to notice,” Kantor said. “You or me, we may kind of feel so happy that we are no longer feeling ill and hacking away that if we start to feel a little coughy again, if we get a little sniffly again, we’d probably just attribute that to kind of a long tail of starting to feel better, but may not even realize, for example, that we would be testing positive again.”

Biden, 79, was treated with the anti-viral drug Paxlovid after he first tested positive on July 21. He tested negative for the virus on this past Tuesday and Wednesday. He was then cleared to leave isolation while wearing a mask indoors. His positive test puts him among the minority of those prescribed the drug to experience a rebound case of the virus.

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

O'Connor cited negative tests for Biden from Tuesday evening, Wednesday morning, Thursday morning and Friday morning, before Saturday morning's positive result by antigen testing. “This in fact represents ‘rebound' positivity," he wrote.

White House COVID-19 coordinator Dr. Ashish Jha told reporters on Monday that data “suggests that between 5 and 8 percent of people have rebound” after Paxlovid treatment.

“The question is, if we were to push this to a seven-day course, to 10-day a course, for example, would we be able to reduce the rate of rebound, while not increasing the risk of side effects?” Kantor said. “I think those are questions that are worth thinking about in the future, particularly because it looks like COVID is something that is here to stay.”

According to the CDC, those with rebound COVID should isolate for at least five days, ending that if a fever has resolved itself for 24 hours without medication and symptoms have improved. The patient “should wear a mask for a total of 10 days after rebound symptoms started. Some people continue to test positive after day 10 but are considerably less likely to shed infectious virus.”

Paxlovid has been proven to significantly reduce severe disease and death among those most vulnerable to COVID-19. U.S. health officials have encouraged those who test positive to consult their doctors or pharmacists to see if they should be prescribed the treatment, despite the rebound risk.

Biden is fully vaccinated, after getting two doses of the Pfizer coronavirus vaccine shortly before taking office, a first booster shot in September and an additional dose March 30.

While patients who have recovered from earlier variants of COVID-19 have tended to have high levels of immunity to future reinfection for 90 days, Jha said that the BA.5 subvariant that infected Biden has proven to be more “immune-evasive.”

“We have seen lots of people get reinfected within 90 days,” he said, adding that officials don’t yet have data on how long those who have recovered from the BA.5 strain have protection from reinfection.