The U.S. Food and Drug Administration (FDA) has ordered Pfizer Inc. to test the effects of an additional course of its antiviral drug Paxlovid among patients who have experienced a “rebound” case of COVID-19. Rebound cases are those in persons who are reinfected after a previous course of treatment with the drug.
The FDA wrote to Pfizer on August 5, giving the company until September 30 to produce a set of initial results from a randomized controlled trial of a second Paxlovid course. Bloomberg reported that it had received confirmation of the accuracy of the letter, which describes regulatory changes in the emergency authorization for Paxlovid.
The FDA specifically called for the test to be conducted as a “placebo-controlled trial in patients with ‘COVID-19 rebound’.” The required test must evaluate a second 5-day treatment course.
But according to Pfizer Paxlovid rebound occurs less than 2% of the time. pic.twitter.com/QpfRLQLVCa
— IT Guy (@ITGuy1959) August 13, 2022
Rebound infection refers to cases in which a person has reported nearly recovering from an initial infection only to test positive again. The most notable rebound infection case has been the one experienced by Joe Biden in recent weeks. During his second infection, Biden suffered occasional coughing and was forced into a second period of isolation. Biden’s top medical advisor Anthony Fauci has also suffered a rebound infection after an initial course of Paxlovid.
Pfizer spokesperson Kit Longley has confirmed that it is “working with the FDA to finalize a protocol to study patients who may be in need of retreatment.” The FDA confirmed that it expects to have a finalized plan for the clinical trial agreed upon before the end of this month.
Paxlovid has become the preferred medication used by practitioners to reduce hospitalization and deaths from COVID-19, especially among high-risk patients. However, since the spring the incidence of rebound infections after an initial course of the medication has multiplied.
Pfizer CEO Albert Bourla has already recommended a second course of the drug in rebound cases. He said in May that if infection returns, “give a second course, like you do with antibiotics, and that’s it.”
However, the FDA responded to that recommendation by saying there is “no evidence” that the second round of Paxlovid would help patients. Pfizer said in July that it was looking into a trial for a second course in conjunction with the FDA.
A study by Case Western Reserve’s Center for Artificial Intelligence in Drug Discovery earlier this year found that there is a rebound infection rate within a month of an initial course of Paxlovid of over 5%.
Pfizer expects to make about $22 billion from the first full year of sales of Paxlovid. When added to the revenue the firm pulls in from the COVID-19 vaccine approved by the FDA, it expects to earn up to $102 billion this year. Pfizer’s stock price is up almost 26% since Joe Biden took office.