WASHINGTON — An aide to Vice President Mike Pence tested positive for the coronavirus, the second administration staffer known to have become infected, an administration official said Friday.

Pence’s flight to Des Moines was delayed by roughly an hour Friday morning, although the staffer who tested positive was not expected to travel with the vice president.

Members of the vice president’s staff who had been in contact with the infected aide were seen deplaning Air Force Two at Joint Base Andrews, an administration official said. The White House medical office is working to identify additional White House staff who were in contact with the individual.

Some White House aides who were in contact with the infected aide have already been retested.

It was not immediately clear if the flight delay was due to the Pence staff member’s positive coronavirus test.

Republican Sens. Chuck Grassley and Joni Ernst of Iowa, as well as Secretary of Agriculture Sonny Perdue, were traveling with Pence on Friday to discuss the impact of the coronavirus on the food supply.

The White House said Thursday that Trump’s personal valet, who works in the West Wing serving the president his meals, among other duties, had tested positive for the coronavirus.

Trump said that the White House would be increasing its testing from once a week to once a day. Trump also said he and Pence tested negative on Wednesday and Thursday.