First lady Jill Biden has tested positive for COVID-19, her communications director said Tuesday.

Biden, 71, tested negative during a regular screening Monday but began to experience symptoms later in the day. She then initially tested negative on a rapid antigen test before testing positive on a PCR test, Communications Director Elizabeth Alexander said in a statement.

Biden, who has been fully vaccinated and boosted twice, is experiencing mild symptoms, Alexander said.

The first lady has been prescribed a course of the oral treatment Paxlovid and will isolate from others for at least five days, according to Alexander. The first lady’s recent close contacts have been notified, the spokeswoman added.

President Joe Biden, Jill Biden and members of their family have been vacationing on Kiawah Island in South Carolina since Wednesday. Jill Biden will remain at a private residence in South Carolina and return home after she receives two consecutive negative COVID tests, Alexander said. 

President Joe Biden tested positive for COVID-19 on July 21 and also experienced mild symptoms. The president tested negative July 27 and began to participate in some in-person events, but three days later, he again tested positive and had to return to isolation. 

According to the White House, Biden tested negative for COVID-19 on Tuesday on an antigen test; the president will mask when indoors and test more frequently because he is a close contact of Dr. Biden.

"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," the White House said in a statement. "We will also increase the President's testing cadence and report those results."

While rare, rebound cases of COVID-19 have been linked to Paxlovid, which Biden took when he was first infected. He tested negative again Aug. 6.

The president is returning to Washington on Tuesday to sign the Inflation Reduction Act, but then will head to Delaware in the evening.

The first lady was set to deliver the opening remarks at Disney’s Veterans Institute Summit at Walt Disney World Resort in Florida later this week.