President Joe Biden tests positive for COVID-19 again

• President Biden tested positive for COVID-19 again on Saturday, after days of testing negative.
• Biden first announced that he tested positive last Thursday, after returning from a foreign trip.

President Joe Biden on Saturday tested positive for COVID-19 a second time after he was initially diagnosed earlier this month and several tests indicated negative results throughout the past week.

Biden's physician, Kevin O'Connor, said in a memo the president tested positive through antigen testing.

"As described last week, acknowledging the potential for so-called 'rebound' COVID positivity observed in a small percentage of patients treated with Paxlovid, the President increased his testing cadence, both to protect people around him and to assure early detection of any return of viral replication," he said.

He continued: "After testing negative on Tuesday evening, Wednesday morning, Thursday morning and Friday morning, the President tested positive late Saturday morning, by antigen testing. This in fact represents 'rebound' positivity."

O'Connor then said that the president was feeling "quite well," but would return to isolation.

"The President has experienced no reemergence of symptoms, and continues to feel quite well," he said. "This being the case, there is no reason to reinstate treatment at this time, but we will obviously continue close observation."

"However, given his positive antigen test, he will reinstate strict isolation procedures. ... [Biden] continues to be very specifically conscientious to protect any of the Executive Residence, White House, Secret Service and other staff whose duties requires any (albeit socially distanced) proximity to him," he added.

Biden on Saturday took to social media to announce that he didn't have symptoms and would be "on the road" sometime in the coming days.

"Folks, today I tested positive for COVID again," he tweeted. "This happens with a small minority of folks. I've got no symptoms but I am going to isolate for the safety of everyone around me. I'm still at work, and will be back on the road soon."

On July 21, the White House announced that Biden tested positive for COVID-19 and was "experiencing very mild symptoms" and had "begun taking Paxlovid," an antiviral drug.

This story has been updated.