(Bloomberg) -- President Joe Biden spent time on Friday with an aide who tested positive for coronavirus infection three days later but has so far tested negative himself, White House Press Secretary Jen Psaki said in a statement.

The aide was in proximity to Biden for about 30 minutes aboard Air Force One on Friday, Psaki said. The aide is fully vaccinated and has had a booster shot, and tested negative before boarding the plane.

But the unidentified aide began experiencing symptoms of Covid-19 on Sunday and tested positive on Monday, Psaki said. Biden is also fully vaccinated and has received a booster. Biden tested negative on Sunday after a rapid antigen test, and negative again on Monday with a more accurate polymerase chain reaction test, or PCR.

He’ll be tested again for infection on Wednesday, but will continue with his daily schedule without quarantining, in accordance with CDC guidance for vaccinated people, she said.

Other people aboard Air Force One who had close contact with the aide will be advised to get tested.

Biden will announce new measures to try to curb the pandemic tomorrow in a speech at the White House, Psaki said earlier on Monday. Cases are again rising in the U.S. as the omicron variant takes hold. The CDC said Monday that the variant, first identified in southern Africa, accounted for 73% of new U.S. cases between Dec. 12 and Dec. 18. 

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