Trump's illness also raised questions about the health of others atop the US government.

Vice President Mike Pence, who would take over if Trump were to fall severely ill, has tested negative, a spokesman said. The former Indiana governor, 61, is working from his own residence several miles from the White House.

Pence took over Trump's planned calls with governors and retirees' organizations. His Oct. 7 debate with Democratic vice presidential candidate Kamala Harris will go forward as planned, organizers said. Harris has also tested negative for the virus, according to the campaign.

House of Representatives Speaker Nancy Pelosi, third in line for the presidency, also tested negative, a spokesman said.

Three journalists tested positive on Friday after spending time over the weekend at the White House or traveling with Trump, according to Zeke Miller, an Associated Press reporter and president of the White House Correspondents' Association.

The Republican National Committee would chose a replacement nominee if Trump were to become incapacitated, but it is already too late in most states to change the names on the ballot. Some 2.9 million people have already voted, according to figures compiled by University of Florida professor Michael McDonald.

The virus could also complicate Trump's push to install conservative judge Amy Coney Barrett on the Supreme Court.

At least two people who were at a White House event to announce her nomination, University of Notre Dame President John Jenkins and Republican Senator Mike Lee, said Friday they have tested positive.

Barrett herself tested positive for the virus earlier this year and recovered, according to a person familiar with the matter.

Trump is the latest world leader to contract the virus, which can cause a severe respiratory infection.

British Prime Minister Boris Johnson was rushed into intensive care after falling gravely ill in March. Brazilian President Jair Bolsonaro called the virus a "little flu" after being infected in July. Both men recovered.

Reuters