FDA: Paxlovid not associated with COVID rebound

Paxlovid isn't associated with COVID rebound, in which patients test positive or have symptoms days after a course of the drug is completed, Food and Drug Administration staff said in briefing documents released Tuesday.

Why it matters: This is the first time the FDA has publicly discussed if the phenomenon is actually due to the antiviral — a question that’s swirled around its use since Pfizer's drug was granted emergency use authorization in December 2021.

The big picture: The documents were prepared ahead of a Thursday meeting of FDA advisers, who will vote on whether to give the pill full approval for patients at high risk of hospitalization or death.

• FDA staff said that Pfizer’s clinical trials support the notion that Paxlovid’s benefits outweigh its risks.

Zoom in: Both the FDA and Pfizer concluded that rebound is likely part of the natural course of a COVID infection and that it does not lead to severe disease when it occurs.

• Rebound has also been observed in the absence of Paxlovid treatment, with potential rates ranging from 10% to 16%.
• The likelihood of rebound was not significantly different between patients who were sick with the omicron variant compared to the delta variant.

What’s next: FDA regulators acknowledged more research is needed to determine whether a longer-term dosage than the customary five-day Paxlovid course could be needed for moderate-to-severely immunocompromised patients.

• One ongoing clinical trial is testing how common COVID rebound is among immunocompromised people.
• Another clinical trial underway is testing the potential benefit of re-treating patients with Paxlovid if they experience a rebound.
• Both are expected to be completed by early December.