Paxilvid is the primary oral medication to prevent severe cases of COVID-19 in people at high risk. However, in some patients symptoms returned after treatment ended, prompting the Centers for Disease Control and Prevention (CDC) to issue a health advisory on the so-called “COVID-19 recovery.”
In a study published on June 20, 2022 in Clinical Infectious DiseasesResearchers at the University of California, San Diego School of Medicine evaluated one of these patients and found that their symptoms relapse was not due to the development of drug resistance or weakened immunity to the virus. Instead, the COVID-19 rebound appears to have been the result of insufficient exposure to the drug.
After a clinical trial showed Paxlovid could reduce the risk of hospitalization and death from COVID-19 by 89%, the drug was made available under an emergency use authorization from the U.S. Food and Drug Administration in December 2021.
The treatment consists of two drugs – nirmatrelvir and ritonavir – that work together to suppress SARS-CoV-2 by blocking an enzyme that allows the virus to multiply in the body. It is easier to take at home than drugs such as Remdesivir, which require an intravenous injection. Treatment should begin within five days of symptoms appearing and taken twice daily for five consecutive days.
The research team, led by lead author Davey M. 19 recovery after baxlovid treatment.
They first isolated SARS-CoV-2 BA.2 virus from a COVID-19 recovery patient and tested whether it had developed drug resistance. They found that after treatment with paxolovid, the virus was still sensitive to the drug and had no related mutations that would reduce the drug’s effectiveness.
said first author Aaron F. Carlin, MD, PhD, assistant professor at the University of California, San Diego School of Medicine. .
The team then took the patient’s plasma to test for immunity to SARS-CoV-2. The patient’s antibodies were still effective in preventing the virus from entering and infecting new cells, indicating that antibody-mediated immunodeficiency was also not the cause of the patient’s frequent symptoms.
The authors said that the rebound of COVID-19 symptoms after Paxlovid treatment ended was likely due to insufficient exposure to the drug: not enough drug reached the infected cells to stop any viral replication. They suggested that this may be because some people metabolize the drug faster or that the drug needs to be taken over a longer treatment period.
Going forward, Carlin said he hopes clinicians can test whether patients need longer treatment with baxlovid or if they can be treated better with a combination drug. In the meantime, Paxlovid users should be aware of the possibility of symptoms recurring and be prepared to wear masks and self-isolate again if symptoms return.
More research is needed to gauge the frequency of relapses, which sick population is most susceptible, and whether a return of symptoms can lead to more serious disease.
“The goal of Baxlovid is to prevent serious illness and death, and so far no one who has ever had the disease again needs to be hospitalized, so they are still doing their job,” Smith said. “We only need to understand why rebound occurs in some patients and not in others. More research is needed to help us adjust treatment plans if necessary.”
Co-authors include: Alex E. Clarke, Antoine Chaillon, Aaron F. Garretson, William Bray, Magali Borachia and Tariq M. Rana, all from UCSD, and Asherleaf T. Santos at California State University in San Marcos.
Material provided by University of California – San Diego. Original by Nicole Mlinarik. Note: Content can be modified according to style and length.
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