Psaki says she was last in contact with President Joe Biden on Tuesday, when she met him in the White House. Psaki says they were more than six feet (183 centimetres) apart and wearing masks.

Psaki is not travelling with Biden, who was in Rome this weekend for the Group of 20 summit and is headed to Glasgow, Scotland, on Monday for a UN climate summit.

Psaki had planned to travel with the president but scrapped the trip just as he was set to depart for Europe after learning that members of her household had tested positive for COVID-19.

“Since then, I have quarantined and tested negative (via PCR) for COVID on Wednesday, Thursday, Friday, and Saturday,” Psaki said in a statement. “However, today, I tested positive for COVID.”

Psaki said she was exhibiting only mild symptoms.

“While I have not had close contact in person with the president or senior members of the White House staff since Wednesday – and tested negative for four days after that last contact – I am disclosing today’s positive test out of an abundance of transparency,” Psaki said.

White House staff and others travelling with the president have been undergoing daily tests for COVID-19 since before departing Washington and are all fully vaccinated.

Biden had his COVID-19 booster on September 27, shortly after federal regulators approved the third dose for many Americans.