“I care less about rebound than I care about preventing serious illness. And Pax did that.”

White House COVID-19 Response Coordinator Ashish Jha speaking at a press conference on July 25. Anna Moneymaker / Getty Images

Even with President Joe Biden testing positive for COVID-19 again on Saturday after he was cleared to exit isolation — in what is known as a “rebound” case — White House Coronavirus Response Coordinator Ashish Jha urges people not to distrust the Pfizer product Paxlovid that may have caused the rebound. 


Rebound cases have been repeatedly observed among people taking Paxlovid, an antiviral treatment from Pfizer that has been proven to reduce risk of hospitalization or death by nearly 90% in high-risk adults. Biden was administered Paxlovid, despite being vaccinated and boosted, for extra precaution when he first came down with COVID-19. 

Jha, currently on leave from his position as dean of the Brown University School of Public Health, took to Twitter Sunday evening to dispel worries, pointing out that even though some people who take Paxlovid are experiencing rebound cases, it’s still doing its job very well.

It’s important to be aware that rebound COVID-19 can happen, for contagion purposes, but generally, it’s not causing serious illness, he said.

Its worth remembering why we use Paxlovid or other therapies

To prevent serious illness and death

Worth remembering: rebound largely doesn’t lead to serious illness

So rebound is not Paxlovid failure

Because the goal is to prevent serious illness – and Pax does that. Well


— Ashish K. Jha, MD, MPH (@AshishKJha46) July 31, 2022

Numbers are hard to know for sure, because most people, whether or not they take Paxlovid, don’t test again immediately after recovery, as Biden did. 

He said his guess is that about 5% of people who take Paxlovid rebound, which is a small minority. And people who don’t take Paxlovid can also rebound. 

“In the clinical trial, the placebo group had almost as much rebound as Paxlovid group,” Jha said. 

So we don’t know how often that happens

Where someone, Pax or no Pax, becomes positive again after testing negative

Because we don’t have a lot of people testing after recovery

But we know from the clinical trials it happens

For folks on Pax — and those not


— Ashish K. Jha, MD, MPH (@AshishKJha46) July 31, 2022

Jeremy Faust, a Brigham and Women’s doctor who writes the Inside Medicine newsletter, posted Saturday that his estimated number of people who rebound is about 15-35% of people who take the drug.

Though he agreed with Jha that Paxlovid is still good to take for preventing serious illness, rebound as a result of Paxlovid is problematic because of contagion, he wrote.

“People who have Paxlovid rebound may be falsely reassured that they’re no longer contagious,” he said. “If they leave isolation and subsequently become contagious again and infect others, they may have inadvertently spread the virus to those far less able to stave off the infection.”

It’s a possibility patients taking Paxlovid should be aware of, according to the CDC.

“If you get better and then you get worse again or if you decide to test and you have a test that’s positive, especially after a negative test result, the recommendation is to re-isolate for at least five more days and continue masking for at least 10 more days,” said Dr. Lauri Hicks, chief medical officer of CDC’s COVID-19 response, in USA Today.

But Jha, on Twitter, maintained that high risk people should still get Paxlovid despite the rebound possibility — “because I care less about rebound than I care about preventing serious illness. And Pax did that.”

But the bottom line is this

Paxlovid is saving lives

Therapeutics are an essential part of fighting this pandemic

And way too many Americans are still dying of COVID

And when it comes to treatments like Paxlovid and monoclonals,

We need to be using more of it, not less


— Ashish K. Jha, MD, MPH (@AshishKJha46) July 31, 2022

Newsletter Signup

Stay up to date on all the latest news from

In Related News