The  Food and Drug Administration (FDA) has asked Pfizer Inc. to test the effects of an additional course of its antiviral Paxlovid among people who experience a rebound in COVID-19 after treatment, the regulator said on Friday.
The drugmaker must produce the initial results of a randomized controlled trial of a second course of the antiviral by Sep. 30 next year, the FDA told Pfizer in a letter dated Aug. 5.
The directive follows reports of recurrent viral infection or symptoms, or both, after the first course, including in President Joe Biden and National Institute of Allergy and Infectious Diseases Director Dr. Anthony Fauci….