HealthDay News — An antiviral drug used to treat high-risk COVID-19 patients may also benefit patients with long COVID, researchers say. The research was posted on a preprint server online and has not been published in a peer-reviewed journal.

Paxlovid has US Food and Drug Administration emergency use authorization to treat COVID-19 patients who are older than 65 years or have underlying health conditions such as obesity, diabetes, or cancer. The pill includes the antivirals nirmatrelvir and ritonavir. Treatment with Paxlovid must start within 5 days of the onset of symptoms and continue for 5 days, according to conditions of the authorization.

Now, a series of case reports from researchers at the University of California, San Francisco (UCSF) shows some success with Paxlovid in treating patients with long COVID. One-third of people infected with COVID-19 are thought to develop symptoms such as fatigue, headaches, and brain fog associated with long COVID. It is thought that long COVID may be caused by the immune system’s ongoing reaction to the virus that remains in the body after the initial infection phase.


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The case reports included 3 patients in their 40s who had symptoms consistent with long COVID. Two started taking Paxlovid weeks after the start of long COVID symptoms, contrary to the emergency authorization conditions. One was prescribed the antiviral after re-exposure to the virus more than 7 weeks after symptom onset, and his health improved to near-normal, according to the researchers. The other patient took Paxlovid about 3 weeks after symptom onset. She felt less fatigued the day after completing therapy but still had shortness of breath and muscle pain.

The third patient started taking Paxlovid within 24 hours of the start of COVID-19 symptoms, in line with the emergency use conditions. His symptoms improved, but returned 4 days after he completed Paxlovid therapy, with fever, runny nose, cough, and chest pain. He also had elevated temperature and heart and respiratory rates. About 2 weeks later, he developed brain fog, chest soreness, fatigue, and discomfort after exertion — symptoms consistent with long COVID.

“The key aspect of this case is that longer courses of Paxlovid may be needed, and giving it too early might not be optimal,” study coauthor Michael Peluso, MD, of UCSF and the Zuckerberg San Francisco General Hospital, said in a news release, noting that there are no safety data yet to support extended use of the drug. “Only by doing rigorous studies will we get answers,” he added. “There is a critical need for this, given the large number of people who have had COVID, a significant subset of whom have long COVID.”

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