WASHINGTON, May 8 (Reuters) - U.S. President Donald Trump on Friday said certain White House staff members have started wearing face masks, one day after the White House said his personal valet had tested positive for the novel coronavirus.

But on Friday, a staffer for Pence tested positive for the virus, briefly delaying the vice president's planned flight to Iowa and raising the specter of contagion for top officials leading the U.S. response to the coronavirus.

Trump, asked whether those who serve him food would now cover their faces, told Fox News in an interview that such White House staff had made that change.

"They've already started," he said on the network's "Fox and Friends" morning program.

The White House on Thursday said Trump and Vice President Mike Pence tested negative for the virus and were feeling well after the staffer - a U.S. military service member who works at the White House as a valet - came down with the virus. It also said the two leaders would now be tested daily, versus weekly.

Trump has said he would not wear a mask and has not publicly worn a mask to any of his events so far amid the COVID-19 pandemic, but told reporters this week that he tried some on behind the scenes during his visit to a Honeywell face mask factory in Arizona.

"As I greet presidents, prime ministers, dictators, kings, queens ... I don't see it for myself, I just don't," Trump said in early April when the Centers for Disease Control and Prevention began recommending widespread mask use to slow the spread of the coronavirus. Read more at Reuters