Miller later confirmed to
NBC News that she tested positive for COVID-19, adding that she's asymptomatic.
The White House did not offer a comment when contacted by Insider.
At least two Trump administration staffers have tested positive for the novel coronavirus, which causes the disease COVID-19, as of Friday.
"We have put in place the guidelines that our experts have put forward to keep this building safe," White House press secretary Kayleigh McEnany said during a press briefing on Friday.
"We clean the facility, we social distance, we keep people six feet away from each other," McEnany added.
News of Miller's exposure came one day after the White House confirmed that a member of the US Navy, who serves as one of Trump's
personal valets, has also contracted the virus. This development reportedly upset the president, and raised questions about his potential exposure to COVID-19.
"The President and the Vice President have since tested negative for the virus and they remain in great health," deputy White House press secretary Hogan Gidley said in
a statement on Thursday.
Trump and Pence have undergone weekly Abbott rapid result tests for the novel coronavirus. The president on Thursday said he will now take daily tests.
Asked why Trump chose not to wear a mask during a visit with World War II veterans on Friday, most whom are in their 90s, McEnany told reporters: "This president is regularly tested. This president will make the decision as to whether to wear a mask or not. I can tell you that those veterans are protected — they made the choice to come here because they've chosen to put their nation first … and I can tell you that the President always puts the safety of our veterans first, and of the American people first."
"We've taken every single precaution to protect the president … and I can assure the American people that their Commander-in-Chief is protected," she added.
Just last week, Pence flouted instructions to wear a face mask during a stop at Mayo Clinic in Minnesota. This decision was widely criticized, prompting Pence to take stock of his actions on
Fox News on Sunday, and acknowledge he made a mistake.
"I don't think it was necessary, but I should have worn a mask at the Mayo Clinic," Pence said.