"On Monday morning, a mid-level staff member, who does not regularly have contact with the president, received a positive result for a COVID-19 test. Three days earlier, on Friday, that staff member had spent approximately 30 minutes in proximity to the president on Air Force One, on the way from Orange, South Carolina to Philadelphia, Pennsylvania", Psaki said.
"The president received an antigen test Sunday, and tested negative. This morning, after being notified of the staffer's positive test, the president received a PCR test and tested negative. He will be tested again on Wednesday", she said.
Psaki said the staff member is fully vaccinated and boosted, and tested negative prior to boarding Air Force One, as required for everyone travelling with the US president.
"As CDC guidance does not require fully vaccinated people to quarantine after an exposure, the president will continue with his daily schedule", she said.