What is Paxlovid, the antiviral that Biden is receiving?
0:48
(CNN) --
President Joe Biden tested positive for COVID-19 again Saturday morning, according to a letter from presidential physician Dr. Kevin O'Connor, in what is likely a "rebound" COVID-19 positivity that the doctor notes that it is “seen in a small percentage of patients treated with Paxlovid.”
According to the White House, Biden has not experienced "any resurgence of symptoms and continues to feel quite well" and will not resume treatment as a result.
According to O'Connor, Biden tested negative Tuesday night, Wednesday morning, Thursday morning and Friday morning before testing positive on Saturday morning.
"However, given his positive antigen test, he will restart strict isolation procedures," the doctor notes.
Biden came out of isolation on Wednesday after successive negative tests for antigens, celebrating her return in remarks from the White House Rose Garden.
Developing note.
Joe Biden