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Rebounding Covid Symptoms After 5-day Paxlovid Treatment

Paxlovid, an antiviral oral drug for Covid-19 infections, doesn't prevent infections, but does prevent hospitalizations and deaths by 90% in high-risk patients.  Risk factors for severe disease, are required to get the drug and include age above 65, and comorbidities like asthma, hypertension, diabetes, obesity etc.  The vast majority of patients who receive Paxlovid report feeling much better after just a few days of treatment.  However, symptoms, which are usually mild, can reappear in 1-2% of patients and then disappear quickly again.  In the randomized placebo-controlled clinical trial rebound of symptoms occurred in the same number of patients receiving Paxlovid and placebo.  There are several theories and a number of studies being done to understand why this occurs, but no definitive explanations have been found as yet.  See Below


There are several studies planned or underway to try to figure out why rebound occurs.  One 71 year old patient was recently studied by looking at daily changes in virus replication, and the numbers decreased during Paxlovid treatment and then increased again for several days.  The first virus peak was on Day 1 of treatment and the second peak was on Day 9, and then quickly decreased again.  This suggests that the patient was contagious again for several days.  Patients who experience rebound of symptoms should consider themselves contagious until rapid antigen tests are negative. There is no evidence that the virus is becoming resistant to Paxlovid.  Perhaps 5 days of drug is not sufficient to eradicate the infection for a small number of patients, although other hypotheses are being tested. Patients who have a rebound should contact their doctor to see if retreatment is necessary. 

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