US Vice-President Mike Pence is self-isolating after an aide tested positive for the coronavirus last week.
A Trump administration official said Mr Pence was voluntarily limiting his exposure and would work from home.
He has repeatedly tested negative for COVID-19 since his exposure but is following the advice of medical officials.
Mr Pence’s spokeswoman Katie Miller, who is married to senior Trump adviser Stephen Miller, tested positive for the coronavirus a day after confirmation that Mr Trump’s personal valet had been diagnosed with the disease.
She had earlier said three members of the White House’s coronavirus task force put themselves in quarantine after having contact with her.
Among them is Dr Anthony Fauci, the director of the US National Institute of Allergy and Infectious Diseases who has become known for his simple and direct explanations to the public about COVID-19.
Mr Pence was informed of the positive test on Friday, before he left Washington for a day-trip to Iowa.
It comes just hours after the administration said it had no plans to keep Mr Pence and President Donald Trump apart, despite concerns about the escalating spread of COVID-19 through the White House.
The New York Times first reported the lack of plans to keep Mr Trump and Mr Pence separated, despite concerns they both could be incapacitated by the disease, citing two senior administration officials.
The White House did not respond to a request for comment.
The president and vice president are leading the US response to the pandemic. Both have resumed travel and business schedules even as the US death toll from the virus nears 80,000.
On Friday, White House press secretary Kayleigh McEnany defended efforts to protect Mr Trump and Mr Pence, pointing to measures taken by the White House including contact tracing and putting in place all guidelines recommended for essential workers.
There are also daily coronavirus tests for the two leaders.
If Mr Trump and Mr Pence – who are Republicans – were both to become incapacitated, Democratic House of Representatives Speaker Nancy Pelosi would assume presidential duties.