US President Joe Biden has tested positive for Covid-19 and is experiencing ”very mild symptoms”, the White House said on Thursday, becoming the second sitting American president to be hit by the virus.

This is the first time Biden, 79, has tested positive for Covid-19.

Biden, who is fully vaccinated and twice boosted, has begun taking the Covid-19 pill Paxlovid.

In line with CDC guidelines, President Biden will isolate at the White House and will continue to carry out all of his duties fully during that time, White House Press Secretary Karine Jean-Pierre said in a statement.

The White House said consistent with its protocol for positive Covid cases, ”which goes above and beyond CDC guidance”, Biden will continue to work in isolation until he tests negative. Once he tests negative, he will return to in-person work.

Biden did not have a fever Thursday morning, the White House's coronavirus coordinator Dr Ashish Jha said. Biden has a runny nose, dry cough and is experiencing some fatigue, Jha was quoted as saying by CNN.

First lady Jill Biden told reporters that she tested negative Thursday morning.

"I talked to him just a few minutes ago. He's doing fine, he's feeling good," she told reporters in Detroit.

"He's feeling good. I tested negative this morning. I am going to keep my schedule," the 71-year-old first lady said.

Biden's positive test result comes days after he returned from a trip overseas where he was in close contact with a number of leaders in Israel and the Middle East.

The White House said it will provide a daily update on the president's status as he continues to carry out the full duties of the office while in isolation.

Biden has been in contact with members of the White House staff by phone this morning, and will participate in his planned meetings at the White House this morning via phone and Zoom from the residence.

Biden's last previous test for Covid was on Tuesday, when he had a negative test result.

Biden is the second sitting US president to get Covid-19 after his predecessor Donald Trump had to be hospitalised with an infection in 2020. Former President Barack Obama also tested positive for Covid-19 in March.

Covid cases along with hospitalisations have been increasing across the US driven by the highly-transmissible BA.5 variant, which recently became the dominant strain in the country.