The wife of US President Joe Biden has tested positive to the coronavirus.

The Bidens have been on holiday in South Carolina since August 10, and the 71-year-old first lady began experiencing symptoms on Monday.

On Wednesday morning (Australian time), White House officials confirmed the first lady was unwell with COVID.

“She tested negative again on a rapid antigen test, but a PCR test came back positive,” spokeswoman Elizabeth Alexander said.

Dr Biden is double-vaccinated and twice boosted. She is isolating and will continue to prepare her teaching work for the upcoming semester.

She has been prescribed the antiviral drug Paxlovid and will isolate at the holiday home for at least five days.

“Close contacts of the first lady have been notified,” her communications director, Elizabeth Alexander, said in a statement on Tuesday.

“She is currently staying at a private residence in South Carolina and will return home after she receives two consecutive negative COVID tests.”

Mr Biden, 79, has been tested multiple times and had returned negative results each time, officials said.

“Consistent with CDC guidance because he is a close contact of the first lady, he will mask for 10 days when indoors and in close proximity to others,” said spokeswoman Karine Jean-Pierre.

“We will also increase the President’s testing cadence and report those results.”

Mr Biden was confirmed with the virus twice during July, his second infection coming just days after he was cleared after his first. At the time, his doctors said it was likely a “rebound case” – which is sometimes the case in patients who have been treated with the antiviral Paxlovid, as Mr Biden was.

The White House said both times that Mr Biden had mild symptoms.

-with AAP