Biden tests positive for Covid-19 again

US President Joe Biden tested positive for Covid-19 on Saturday morning, after apparently recovering from the virus and testing negative on Tuesday. Biden’s physician explained that he likely suffered a so-called “rebound” infection, which can affect patients taking Pfizer’s antiviral pill.

Biden’s positive test was announced by White House physician Kevin O’Connor, in a letter to Press Secretary Karine Jean-Pierre. O’Connor noted that Biden had tested negative for the illness every day since Tuesday, but would re-enter isolation following Saturday morning’s positive result.

Prior to Tuesday’s negative test, Biden had worked in isolation in the White House for five days, while suffering mild symptoms.

Biden, who has been vaccinated twice and received two booster doses, also took Pfizer’s Paxlovid, an antiviral medication given emergency authorization by the Food and Drug Administration (FDA) in December. 

O’Connor noted that “a small percentage of” patients treating Covid-19 with Paxlovid are likely to suffer so-called “rebound Covid positivity” – where they seem to recover from the disease before falling ill again. In Biden’s case, the president has “experienced no reemergence of symptoms, and continues to feel quite well,” O’Connor wrote.

White House coronavirus czar Dr. Anthony Fauci also suffered such a reinfection when he treated his case of Covid-19 with Paxlovid in May.

Following his negative test earlier this week, Biden described Paxlovid as a “game-changer” in the fight against Covid-19, and urged Americans to obtain the pills from drugstores around the country.