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COVID-19 Rebound Probably More Common Than Data Suggests, But Doesn't Detract From Paxlovid

2022-08-26T17:15:09.336Z


Experts say rebound cases are probably more common than the data suggests, but it's hard to know exactly to what extent.


What is Paxlovid, the antiviral that Biden is receiving?

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(CNN) --

As the coronavirus evolves, the number of treatment options that remain effective against new variants has dwindled.

The antiviral drug Paxlovid is one of the few that remain effective.


However, some people who take Paxlovid, and some who don't, experience a rebound case of COVID-19, in which their symptoms resurface or they test positive just days after completing treatment and testing negative.

And some high-profile rebound cases, including against President Joe Biden, Dr. Anthony Fauci and First Lady Jill Biden, raise questions about how often these cases actually happen.

"From the data we have so far, rebound cases of COVID-19 are relatively rare events, not something that happens in most cases," a spokesperson for the Centers for Disease Control told CNN. U.S. Disease Control and Prevention (CDC) "A small percentage of people with COVID-19 experience a rebound of symptoms, including those who took antiviral drugs such as Paxlovid."

Experts say rebound cases are probably more common than the data suggests, but it's hard to know exactly to what extent.

There is a wide range of estimates of what that "small percentage" might be, from less than 1% of people taking Paxlovid to more than 10%, and definitions of a rebound case lack consistency.

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And a "brief return of symptoms may be part of the natural history of SARS-CoV-2 (the virus that causes covid-19) infection in some people, regardless of Paxlovid treatment and vaccination status," according to a health advisory issued by the CDC.

Better understanding of the details is important, both for individual patients and the community at large, says Michael Charness, MD, of the Veterans Administration Medical Center in Boston, who has collaborated with a team of researchers at Columbia University to study cases of covid-19 that reappear after treatment with Paxlovid.

People who experience a rebound case can be contagious, so they should be aware of the possibility that they may need to re-isolate according to CDC guidance, he said.

And for others, the return of symptoms or a positive test can "certainly be a source of concern for many people, wondering 'Why is this happening to me?'

  • What should we know about Paxlovid rebound?

    Our medical analyst explains

Tracking the rebound of covid-19

In clinical trial documents submitted to the US Food and Drug Administration (FDA) last year, Pfizer noted that "several subjects appeared to have a rebound in SARS-RNA levels." CoV-2".

Their data shows that about 2% of people showed a present or persistent viral load rebound, a percentage that was similar between those treated with Paxlovid and the placebo group that was not.

Pfizer has no additional data on rebound cases beyond clinical trials, which were conducted during a time when the delta variant was dominant and most people were unvaccinated.

A preprint study tracking rebound cases during the omicron surge found that 2-4% of patients experienced a rebound infection or symptoms one week after treatment, and 5-6% had a rebound within a month.

Another study published in June by Mayo Clinic researchers largely matched data from the Pfizer clinical trial.

The researchers found that about 1% of Paxlovid-treated patients experienced a rebound of symptoms, an average of about nine days after treatment.

The study was retrospective and could not determine if patients tested positive along with return of symptoms.


However, according to Aditya Shah, an infectious disease specialist and author of the report, the true rate is probably closer to 10%.

"You have to recognize the limitations of doing this type of study. All of these patients are at home, and not all patients who have rebound symptoms are going to contact their doctor," Shah said.

"So our study was definitely underrepresenting the actual cases."

Charness also estimates the COVID-19 rebound rate for vaccinated people who have taken Paxlovid to be in a similar range, but uncertainty remains.

"There hasn't been any study that gives us a clear answer. It's probably not 50%, and it's probably not 2%," he said.

"I wouldn't be surprised if it was in that range of 5 to 10% for people who are treated in the range of 1 to 2% in people who are not treated."

According to the CDC, preliminary data suggests that people with comorbidities may be more likely to experience a rebound case.

However, studies to examine risk factors are "ongoing" and "there is inconclusive evidence at this time and more research is needed," they said.

  • Why did Joe Biden have a rebound from covid-19?

    We explain the phenomenon that occurs with the drug Paxlovid

"The rebound will be an inconvenience"

Despite the possibility of a rebound case, experts agree that Paxlovid remains a good treatment option.

A rebound case of Covid-19 is one of the costs of taking Paxlovid, but it must be weighed against the costs of what could happen without treatment, Charness said.

The vast majority of people who have a rebound case of covid-19 after taking Paxlovid have mild symptoms.

Sometimes they may come back stronger, as in the case of Fauci, but they are still far from the levels of serious illness that Paxlovid claims to protect against.

  • What advantages and disadvantages would the use of Paxlovid against covid-19 have?

"I think, especially for people who are at significant risk of progression, it's important to take Paxlovid," he said.

"A percentage of those people, yet to be determined, are going to rebound. But for almost all of those people, rebound is going to be an inconvenience. And that inconvenience is really not as important as the possibility of avoiding hospitalization or death." death".

Both President Biden and Fauci received a second course of Paxlovid to deal with their rebound cases.

And just this week, the FDA has requested more data from Pfizer to study patients who may need a second treatment.

"While further evaluation is needed, we continue to monitor data from our ongoing clinical studies and post-authorization safety surveillance," Pfizer said in a statement.

"We remain very confident in its clinical efficacy in preventing serious outcomes of COVID-19 in patients at highest risk."

In general, public data on Paxlovid prescriptions is sparse.

According to the US Department of Health and Human Services, some 4 million completed courses of Paxlovid had been administered as of mid-August, but there are no additional details on the demographics or health status of those who have received it.

As for the ricochet cases, Charness says a lot of work has been done, but a lot of questions remain.

“I go back to February and March when this was something that was really not known and when people experiencing rebound were calling their providers and being told that the test must be wrong,” he said.

"Between then and now, there's been a huge spread of information, which is good, but people aren't 100% sure how to handle it."

Paxlovidcovid-19 outbreak

Source: cnnespanol

All news articles on 2022-08-26

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