Update 7/30/2022, 4:00pm ET: Late this Saturday morning, President Joe Biden once again tested positive for SARS-CoV-2, marking the start of a COVID-19 "rebound."

According to the president's physician, Kevin O'Connor, Biden is not experiencing any renewed symptoms and "continues to feel quite well." However, due to the positive rapid antigen test, he will re-enter isolation.

Biden, 79, first tested positive for SARS-CoV-2 Thursday, July 21 while experiencing mild symptoms. He immediately began a five-day course of the antiviral Paxlovid, which had ended by Tuesday, July 26, when he tested negative on a rapid antigen test. He continued to test negative on Wednesday, Thursday, and Friday before testing positive again today.

Given his current lack of symptoms, O'Connor said Biden is not starting another round of Paxlovid. But the president will remain under close observation.

Notably, top infectious disease expert, Anthony Fauci, 81, also experienced a COVID-19 rebound after a five-day course of Paxlovid in June. He reported that his rebound symptoms were "much worse" than his initial case and took a second five-day course of Paxlovid.

Original story 7/27/2022, 11:01am ET:President Joe Biden has now tested negative for SARS-CoV-2 on two separate rapid antigen tests, and he is ending his "strict isolation measures."

Advertisement

The president tested negative Tuesday evening and then again on Wednesday morning, the president's physician, Kevin O'Connor, wrote in his daily update letter of the president's SARS-CoV-2 infection.

Biden, 79, first tested positive Thursday morning while experiencing mild symptoms of a runny nose, fatigue, and a dry cough.

After the diagnosis, he immediately went into isolation and began a five-day course of the antiviral Paxlovid. He completed that course 36 hours ago, O'Connor wrote. The president is fever-free, and the rest of his symptoms are improving and are "almost completely resolved."

Biden will now leave his isolation but will wear a well-fitting mask for 10 days. The decision to end isolation exceeds the standards set by the Centers for Disease Control and Prevention, which does not require negative tests to end isolation. The agency advises that people can end their isolation after five days, without a test, as long as they are fever-free and their symptoms are improving, but they should mask until 10 days after testing positive.

O'Connor ended the letter by noting the possibility that Biden could experience a COVID "rebound" following his course of Paxlovid. It's unclear why, but some people with COVID-19 experience a resurgence of symptoms and again test positive after an initial but brief recovery. This phenomenon has been particularly reported in patients who take Paxlovid, but the percentage of people who experience a rebound remains unknown.

"The President will increase his testing cadence, both to protect people around him and to assure early detection of any return of viral replication," O'Connor wrote.