(NewsNation) — President Joe Biden tested negative for COVID-19 for the second day in a row, ending his most recent isolation, following a rare “rebound” case.
“This morning, the President’s SARS-CoV-2 antigen testing was negative for a second consecutive day. He will safely return to public engagement and presidential travel,” Dr. Kevin C. O’Connor said in a letter to the president Sunday morning.
Biden left the White House for the first time since becoming infected with the coronavirus last month, settling in for a reunion with first lady Jill Biden in their home state of Delaware.
“I’m feeling great,” Biden said before boarding Marine One outside the White House.
The president continued to isolate throughout the day Saturday as a precaution despite testing negative for the illness.
Biden, who is fully vaccinated and twice boosted, first tested positive for COVID-19 in July, with mild symptoms. He was treated with the anti-viral drug Paxlovid.
He tested positive for the coronavirus again later that month, in a rebound case that is “extremely uncommon,” according Dr. Anthony Harris, CEO of Hfit Health.
“It’s about 1% of the population treated with Paxlovid that experience a rebound,” Harris told NewsNation “The good news is that we shouldn’t be seeing this occur in the general population.”
White House COVID-19 coordinator Dr. Ashish Jha said data “suggests that between 5 and 8% of people have rebound” after Paxlovid treatment.
The Associated Press contributed to this report.
President Joe Biden walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden waves as he walk to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden puts on his mask back as he walks closer to Marine One on the South Lawn of the White House in Washington, Sunday, Aug. 7, 2022, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden steps off Marine One at Cape Henlopen State Park in Rehoboth Beach, Del., Sunday, Aug. 7, 2022. (AP Photo/Patrick Semansky) 
President Joe Biden salutes as he boards Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden walks from the Diplomatic Room to board Marine One at the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden takes off his mask as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden waves as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden responds to reporters questions as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden responds to reporters questions as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden responds to reporters questions as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta) 
President Joe Biden responds to reporters questions as he walks to board Marine One on the South Lawn of the White House in Washington, on his way to his Rehoboth Beach, Del., home after his most recent COVID-19 isolation, Sunday, Aug. 7, 2022. (AP Photo/Manuel Balce Ceneta)