US President Joe Biden again tested positive for the coronavirus on Saturday, according to a statement from the White House physician, although he is experiencing no symptoms and feels "quite well."
Mr Biden, who tested positive for the virus nine days ago but then tested negative twice earlier this week, will resume isolation procedures, and his positive test is believed to be "rebound" positivity experienced by some patients, according to Dr Kevin O'Connor.
Mr Biden tweeted about his positive case, saying it can happen to 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," he wrote.
The positive test jeopardises a trip to Michigan Mr Biden had planned for Tuesday to promote recent legislation to boost the semiconductor industry, which the White House announced on Saturday.
Dr O'Connor said Mr Biden, who is 79, tested negative for the last four days, and there is no plan to reinitiate treatment given his lack of symptoms.
Mr Biden previously described his experience with the coronavirus as mild, saying he was able to continue working while in isolation and attributed his relative ease with the disease to vaccines and other treatments.
Dr O'Connor had previously said Mr Biden would be tested regularly to watch for a potential "rebound" case, which can be experienced by some patients who have been treated with Paxlovid, the drug the president received.