Covid can rebound even in people who haven’t taken Paxlovid, study finds

About a third of people with Covid will see a recovery in their symptoms regardless of whether they have been treated with the antiviral Paxlovid, according to a study published online on Tuesday.

The pre-print study – meaning it has not been published in a peer-reviewed journal – found that 27% of people with Covid saw a rebound in their symptoms after they had initially improved.

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“It happens all the time. People who don’t get treatment for Covid and then feel better can develop symptoms later,” said study co-author Dr. Davey Smith, chief of infectious diseases and global public health at the University of California, San Francisco School of Medicine. San Diego.However, Smith noted that the 27% finding was higher than what he expected based on anecdotal evidence.

The study also found that 12% of people with Covid had “viral rebound”, meaning they tested positive again several days after testing negative. This has been documented among people who received Paxlovid and is referred to as Paxlovid rebound, but the study found that viral rebound occurred regardless of whether a person had received the antiviral treatment.

Anyone who has had Covid could see a re-emergence of symptoms after they have gone away, and those symptoms may be worse or not as bad as the first period, Smith said. “It’s just the variability in the natural course of infection.”

The Centers for Disease Control and Prevention has acknowledged the possibility of symptoms reoccurring in untreated Covid patients. When the agency in May issued a health alert notifying doctors of Paxlovid rebounds, it also said that “a brief return of symptoms may be part of the natural history of SARS-CoV-2 (the virus that causes COVID -19) in some individuals, regardless of Paxlovid treatment and regardless of vaccination status.’

The hair removal and symptom reduction phenomenon is not unique to Covid.

“In a way, this is the natural history of all respiratory viral infections,” said Dr. Paul Sachs, clinical director of the division of infectious diseases at Brigham and Women’s Hospital in Boston. “There are good days and bad days, and then they eventually get better.”

Paxlovid rebounds, in particular, have received a lot of attention in recent weeks, with President Joe Biden and his chief medical adviser, Dr. Anthony Fauci to be positive several days after taking the antiviral.

In Pfizer’s clinical trial of the drug, 1% to 2% of people who received Paxlovid tested positive for the coronavirus after testing negative. In a newsletter for doctors prescribing Paxlovid, the drugmaker noted that this also happened at similar rates among the placebo group.

But even if a person has taken Paxlovid, it’s still hard to tell if their recovery is explicitly caused by the drug.

“It could be that what would have happened without Paxlovid is that they would have tested positive in those last few days, but they would not have had the interim negative test. … This could just be a small perturbation in what was the natural history of the disease for them,” Sachs said.

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Smith agreed: “The symptoms fluctuate and the viral antigen in the nose fluctuates and fluctuates with and without Paxlovid.”

Dr. Albert Ko, an epidemiologist at the Yale School of Public Health, said that regardless of the symptoms of recovery, the message is clear: Paxlovid works.

“Paxlovid does what it’s supposed to do: prevent us from life-threatening Covid,” Ko said. “Even though these rebounds happen, it prevents serious effects.”

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