US Vice President Mike Pence's press secretary has the coronavirus, the White House says, making her the second person who works there known to test positive for the virus this week.
President Donald Trump, who publicly identified the affected Mr Pence aide, said he was "not worried" about the virus spreading in the White House.
Nonetheless, officials said they were stepping up safety protocols for the complex.
Pence spokeswoman Katie Miller, who tested positive on Friday, had been in recent contact with Mr Pence but not with the president.
President Donald Trump's personal valet recently tested positive to coronavirus. Source: AAP
She is married to Stephen Miller, a top Trump adviser. The White House had no immediate comment on whether Mr Miller had been tested or if he was still working out of the White House.
Katie Miller had tested negative on Thursday, a day before her positive result.
"This is why the whole concept of tests aren't necessarily great," Mr Trump said.
"The tests are perfect but something can happen between a test where it's good and then something happens."
The positive test for Mr Pence's aide came one day after White House officials confirmed that a member of the military serving as one of Mr Trump's valets had tested positive for COVID-19.
Six people who had been in contact with Mr Miller were scheduled to fly with Mr Pence on Friday to Des Moines, Iowa, on Air Force Two. They were removed from the flight just before it took off, according to a senior administration official.
None of those people were exhibiting symptoms, but were asked to deplane so they could be tested "out of an abundance of caution," a senior administration official told reporters travelling with Mr Pence. All six later tested negative, the White House said.
The official said staff in the West Wing are tested regularly but much of Mr Pence's staff - which works next door in the Executive Office Building - are tested less frequently. Katie Miller was not on the plane and had not been scheduled to be on the trip.
Mr Pence, who is tested on a regular basis, was tested on Friday.
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