When Dr. Anthony Fauci got Covid in June after receiving Paxlovid, an antiviral drug for people with mild to moderate symptoms who are at increased risk of severe disease due to their age or immune status. Treatment consists of three tablets per day for five days.
Fauci has completed treatment and tested negative for Covid. But three days later, the test came back positive. Her symptoms — runny nose, sore throat and fever — returned.
A small minority of people who take Paxlovid experience similar relapses.
“When you look at the studies, it’s not very common,” Fauci, who heads the National Institute of Allergy and Infectious Diseases and is President Joe Biden’s chief medical adviser, told MSNBC’s “Morning Joe” on Tuesday. But he notes that there have been “anecdotal cases” where rebounds are now more common than in clinical trials.
In Pfizer’s clinical trial, about 1% to 2% of people who took Paxlovid tested positive for the coronavirus after testing negative. White House Covid Response Coordinator, Dr. Ashish Jha said at a press conference last week.
“If you look at Twitter, it seems like everything is back up,” Jha said. “But there’s actually clinical data.”
A small study in June found that less than 1% of Covid patients recovered from their symptoms within an average of nine days after taking Paxlovid. In a large, non-peer-reviewed study of 13,600 Covid patients, 6% had symptoms return within a month of treatment.
Dr. Aditya Shah, an infectious disease specialist at the Mayo Clinic who led the small study, said it’s difficult to self-diagnose cases where people recover. Ideally, people would be able to prove they tested positive, then negative, then positive again, he said.
The actual number of rebound cases “could be as high as 5-10%, but I don’t think it’s as common as the general public is saying,” Shah said.
The Centers for Disease Control and Prevention noted in May that symptoms usually return two to eight days after paxlovid is stopped, if they do return.
People who continue to test positive may still be contagious, so the CDC recommends that people begin isolating for at least five days if their illness returns.
Treatment may not last long
Some disease experts suspect that the Paxlovid regimen is too short to clear the virus in some people.
“One theory is that your natural immunity doesn’t kick in quickly because you have to be treated within five days of symptoms, so it’s early in the course of the disease,” said Dr. Peter Gulick, associate professor of medicine at Michigan State University.
When someone takes Paxlovid, “it lowers the viral load to a point where the body doesn’t react clinically with any inflammation,” Gulick said. These symptoms usually resolve within five days.
But some people may still have viruses in their bodies, especially if they have high viral loads or if the virus has spread to areas where drugs are not easily accessible. In this case, the symptoms may return.
“It could even be reservoirs,” Gulik said. “We don’t know the ability of Paxlovide to get into some of the smaller areas of the body where the virus might be.”
Shah does not believe that extending the course of treatment will benefit patients: “I would hesitate to say now, ‘Yes, of course, do a 10-day course,’ because there is no evidence to support this.”
Disease experts say that elderly or immunocompromised people may experience a relapse of symptoms or test positive after taking Paxlovid, but there is no good data to support the theory.
In any case, the symptoms of the disease should be mild. A June CDC study found that fewer than 1% of people taking Paxlovid were hospitalized or hospitalized for Covid-19 within 5 to 15 days of stopping treatment.
“Paxlovid is working really well and preventing serious disease, relapses or relapses,” Jha said last week. Therefore, the president accepted,” he said.
Biden completed a five-day course of Paxlovid on Monday. Experts say he should find out in the next few days if his symptoms flare up again.