One in Five Patients Experience Rebound COVID After Taking Paxlovid, New Study Finds

Nov 13, 2023
6 minute read

While Paxlovid remains a ‘life-saving drug,’ Mass General Brigham researchers found that patients experiencing virologic rebound after treatment may remain contagious

A new study by investigators from Mass General Brigham found that one in five individuals taking Nirmatrelvir-ritonavir therapy, commonly known as Paxlovid, to treat severe symptoms of COVID-19, experienced a positive test result and shedding of live and potentially contagious virus following an initial recovery and negative test—a phenomenon known as virologic rebound. By contrast, people not taking Paxlovid only experienced rebound about 2 percent of the time. Results are published in Annals of Internal Medicine.

“We conducted this study to address lingering questions about Paxlovid and virologic rebound in COVID-19 treatment,” said corresponding author Mark Siedner, MD, MPH, an infectious disease clinician and researcher in the Division of Infectious Diseases at Massachusetts General Hospital. "We found that the virologic rebound phenomenon was much more common than expected—in over 20% of people taking Paxlovid—and that individuals shed live virus when experiencing a rebound, implying the potential for transmission after initially recovering from the virus."

Paxlovid is an oral antiviral medication used to treat COVID-19. Previous studies demonstrate the medication's effectiveness in reducing hospitalization and death in cases of severe COVID-19 infection. Since the integration of Paxlovid into COVID-19 treatment, some patients have reported virologic rebound. A previously conducted phase 3 clinical trial known as EPIC-HR suggested that only 1% to 2% of patients taking Paxlovid experienced virologic rebound. However, the study by Siedner and colleagues suggests this phenomenon occurs far more often than previously suspected.

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