“This isn’t a matter of politics,” Mr. Biden mentioned at a gathering in Grand Rapids, Mich., whereas sporting a masks. “It’s a bracing reminder for all of us that we should take this virus significantly. It’s not going away. We should all do our half to be accountable. Meaning following the science, listening to specialists.”

Mr. Trump by his personal admission has performed down the severity of the virus, repeatedly declaring that it might vanish by itself, pressuring faculties, companies and sports activities leagues to reopen, disputing the warnings of his personal public well being specialists and questioning the effectiveness of face masks. He defied well being pointers by internet hosting marketing campaign rallies and different occasions crowded with supporters who principally didn’t put on masks or keep social distance. Solely hours earlier than his personal constructive take a look at, Mr. Trump insisted in a speech that “the tip of the pandemic is in sight.”

Nobody might say for certain when the president was contaminated, however the White Home medical unit was centered on his ceremony within the Rose Backyard final Saturday the place he introduced his nomination of Decide Amy Coney Barrett for the Supreme Courtroom, an occasion the place many officers and visitors mingled with out masks and with out maintaining distance.

A number of visitors and reporters who have been current or traveled with the president on Air Drive One later that night examined constructive on Friday, together with Senators Mike Lee of Utah and Thom Tillis of North Carolina, each Republicans; the Rev. John I. Jenkins, the president of College of Notre Dame; Kellyanne Conway, the president’s former counselor; and Michael D. Shear, a White Home correspondent for The New York Instances. Decide Barrett beforehand recovered from the coronavirus.

Mr. Trump is the most recent world leader to become infected. Prime Minister Boris Johnson of Britain was so sick that he had to be hospitalized before later recovering. Prince Charles likewise contracted the virus, as have the leaders of Brazil, Honduras, Guatemala and Bolivia. However Mr. Trump has repeatedly dismissed issues about his well being, telling advisers that the coronavirus is a roll of the cube.

Whereas the virus is far deadlier than the unusual flu, the overwhelming majority of individuals contaminated by it recuperate, particularly if there isn’t a underlying situation, however the menace climbs with age. At 74, Mr. Trump is in probably the most weak class, with the chance elevated due to his weight, which is categorized as overweight. Eight out of every 10 deaths attributed to the virus in america have been amongst these 65 and older.

Mr. Trump is conscious of these numbers and lengthy mentioned that older Individuals have been extra in danger. For all his public dismissal of the coronavirus, advisers mentioned Mr. Trump has been haunted by the demise of a New York pal from his enterprise days, Stanley Chera, 78, who went into the hospital with the coronavirus and by no means got here out.