Joe Raedle
The recurrence of COVID-19 symptoms in patients who received Paxlovid therapy from Pfizer (NYSE:PFE) is not uncommon, with potential for transmission during the rebound period, according to a newly published study.
President Joe Biden and his chief medical advisor Dr. Anthony Fauci are among some of the high-profile cases to have experienced COVID rebound following Paxlovid therapy.
The five-day Paxlovid treatment consisting of protease inhibitor nirmatrelvir and the antiviral ritonavir is authorized in the U.S. to treat mild-to-moderate COVID-19 in those aged 12 years and above who are at high risk of progressing to severe disease.
Amid reports of disease rebound following Paxlovid therapy, Pfizer (PFE) said that the incidence of such cases was consistent with the data from the EPIC HR Phase 2/3 trial, which the company used to obtain regulatory clearance for the treatment.
The study published in The New England Journal of Medicine this week has looked at the occurrence of rebound symptoms and the viral replication in 13 patients aged 29 – 71 years who received Paxlovid.
The patients, none of whom were immunocompromised, were fully vaccinated and had received at least one dose of a messenger RNA vaccine booster 15 days – seven months before the diagnosis.
Rapid antigen testing indicated that rebound results turned strongly positive on Day 9 – 15 following the treatment, and the positivity remained for 2 – 7 days and took as late as Day 22 to turn negative. All patients recovered without further antiviral therapy.
The researchers noted that two of them might have transmitted the disease during the rebound period, adding that five cases occurred within two families, which they said: “suggests that rebound after nirmatrelvir–ritonavir therapy is not uncommon.”
The investigators warned that the evidence, such as higher viral load and potential transmission, implies that patients who experience disease recurrence could be contagious during the rebound period.
“Additional data are needed to determine the cause, frequency, duration, and spectrum of rebound symptoms along with the relation to antiviral treatment,” the researchers wrote.
The trouble of rebound “should not dissuade people” from taking the medication, lead study author Michael Charness, chief of staff of the VA Boston Healthcare System, said.
“Given the large numbers out there who will be taking Paxlovid, we just wanted people to be aware,” he added.
In August, the FDA ordered Pfizer (PFE) to conduct a clinical trial to test a second course of Paxlovid in those who experience COVID rebound following the treatment.
