FDA directs Pfizer to test second dose of Paxlovid for ‘rebound’ infections

The Food and Drug Administration is directing U.S. biomedical company Pfizer to produce a second round of tests for its COVID-19 antiviral drug to treat those who suffer from “rebound” infections.

The FDA said in a letter to Pfizer earlier this month that the company would be required to “conduct a randomized placebo-controlled trial in patients with ‘COVID-19 rebound’ following an initial treatment course of PAXLOVID to evaluate a subsequent 5-day treatment course of PAXLOVID.”

“Pfizer will provide topline results by September 30, 2023,” the agency said. 

“Rebound infections” have been reported among individuals who appear to have nearly recovered from COVID, with the most notable being that experienced by President Joe Biden last month into this month. 

The letter was first reported on by Bloomberg this week, to which Pfizer confirmed that it was “working with the FDA to finalize a protocol to study patients who may be in need of retreatment.”