Paxlovid does not lower risk of long-term COVID-19 symptoms, UCSF study shows

SAN FRANCISCO -- The popular COVID treatment, Paxlovid, does not significantly lower the risk of "long COVID" for people who are vaccinated.

In a new study from UCSF, researchers found that patients who took Paxlovid and those who did not had similar outcomes when it came to long COVID symptoms.

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Researchers also found a higher-than-expected COVID rebound for patients who took the medication.

Paxlovid has been shown to be effective for high-risk, unvaccinated people.

"Our study, as well as two other really well-done studies, now have come out with the same results using slightly different approaches," said Dr. Matt Durstenfeld, assistant professor of medicine at UCSF. "I feel pretty confident that together, our studies really suggest that the Paxlovid, unfortunately, does not really prevent long COVID."

Durstenfeld said that they surveyed thousands of volunteers who were vaccinated and didn't have COVID before Paxlovid came out.

They surveyed the volunteers once they were infected and then later again after they took Paxlovid to see if they had long COVID symptoms.

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"What we found was that actually taking Paxlovid at the time that you have COVID, during the acute infection does not seem to be associated with a lower risk of having long COVID down the road among the people who are already vaccinated and having their first infection," he said.

Durstenfeld said that researchers also found a higher-than-expected number of patients getting COVID rebound symptoms after taking Paxlovid.

ABC7 reached out to Pfizer, who makes Paxlovid.

In a statement, it said:

"As we've established, we intend to provide significant medical contributions across the COVID-19 disease spectrum, from prevention with vaccines to therapeutics that help patients avoid or address severe outcomes of disease. Though we do not currently have any Pfizer-sponsored long COVID studies underway, we are continuing to monitor data from our clinical studies and real-world evidence, and welcome independent research and academic discourse on long COVID. PAXLOVID is not authorized or approved for use as a treatment or prophylactic for long COVID.

"It is important to note that PAXLOVID has been a breakthrough in the fight against COVID-19, helping to treat millions of high-risk patients across the U.S. and millions more around the world. In clinical trials, PAXLOVID reduced the risk of COVID 19-related hospitalization or death by 86%. Real-world analyses conducted across age groups,vaccination status, and predominant variants, reinforce the benefit-risk profile of PAXLOVID, its role in helping to treat patients with COVID-19 who are at high risk for progression to severe illness, and the value it offers to the health care system and eligible patients."

As it relates to rebound symptoms, Pfizer said:

"We believe COVID-19 rebound is uncommon and not uniquely associated with any specific treatment. We remain very confident in PAXLOVID's clinical effectiveness at preventing severe outcomes from COVID-19 in patients at high risk."

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Pfizer also pointed to this CDC report, titled "SARS-CoV-2 Rebound With and Without Use of COVID-19 Oral Antivirals."

Despite the UCSF study, Durstenfeld reiterates that Paxlovid is still an important treatment to prevent disease in people at high risk of severe COVID.

"I think there are still a group of people, particularly people who are at very high risk of having severe COVID-19, which fortunately is much less common these days. But there still are people who are immunosuppressed or people who have other reasons why they might be at higher risk." he said. "And if there's anybody who's not vaccinated, they certainly still remain at higher risk than people who are vaccinated. I think where our study kind of helps is those people who are at low risk but are taking Paxlovid and purely to try to prevent long COVID. I think it weakens the evidence for that."