WASHINGTON — President Trump was hospitalized on Friday evening after learning he had the coronavirus and experiencing what aides called coughing, congestion and fever, throwing the nation’s leadership into uncertainty and destabilizing an already volatile campaign only 32 days before the election.
Mr. Trump was flown to Walter Reed National Military Medical Center after being given an experimental antibody treatment as the White House rushed to cope with a commander in chief infected by a virus that has killed more than 208,000 people in the United States. Officials said he would remain in the hospital for several days and canceled upcoming campaign events.
The White House shrouded Mr. Trump’s condition in secrecy, saying little more than that he had “mild symptoms,” and officials characterized the hospital stay as a precautionary measure. But the normally voluble president remained almost entirely out of public view, skipped a telephone call with governors at the last minute and uncharacteristically stayed off Twitter nearly all day while people close to the situation said his fever and other symptoms worsened as the hours wore on.
“I want to thank everybody for the tremendous support,” Mr. Trump, wearing a suit and tie but appearing unusually pale and lethargic, said in an 18-second video taped just before getting on the Marine One helicopter and then posted on Twitter in his first public comment of the day. “I’m going to Walter Reed hospital. I think I’m doing very well, but we’re going to make sure that things work out.”
The president donned a black face mask and emerged from the White House shortly after 6 p.m., giving a perfunctory thumbs up to reporters without stopping to speak as he walked unassisted to the helicopter. He was accompanied by Mark Meadows, the White House chief of staff, who was also wearing a mask.
The hospital trip was an abrupt change in plans after Vice President Mike Pence had told governors earlier in the day that the president would remain at the White House. One administration official said it would be better for Mr. Trump to leave on his own while he still could rather than risk getting sicker and having the image of being taken out of the White House with assistance. If he gets better, the official said, the Walter Reed stay will have been inconsequential politically.
Dr. Sean P. Conley, the president’s physician, said in a statement that Mr. Trump, while still at the White House, received a single 8-gram dose of polyclonal antibody cocktail while also taking zinc, vitamin D, melatonin, aspirin and famotidine, a heartburn medicine. But Walter Reed has equipment that would allow better monitoring of his condition and a quick response if he has trouble breathing or experiences other symptoms.
Hours later, shortly before midnight, Dr. Conley said in a new statement that Mr. Trump was “doing very well” and “not requiring any supplemental oxygen,” but was put on remdesivir, an antiviral drug that has hastened the recovery of some coronavirus patients.
Around the same time, Mr. Trump, in his first tweet of the day other than the video, which may have been posted by his staff on his account, wrote, “Going welI, I think! Thank you to all. LOVE!!!”
The president’s illness touched off a cascade of concern, suspicion, calculation and recrimination in response to a president hospitalized with a potentially life-threatening health condition for the first time in nearly 40 years. The White House was left in a state of shock while the capital pondered what-if scenarios in case the situation worsens.
The sudden development could have unforeseen consequences. It could on the one hand complicate Mr. Trump’s drive to confirm a new Supreme Court justice before the election on Nov. 3 while giving new impetus to long-stalled talks for another round of coronavirus relief spending, according to officials.
The first lady, Melania Trump, and the president’s close adviser Hope Hicks were also infected, as was Ronna McDaniel, the Republican National Committee chairwoman, who was last with Mr. Trump a week ago, on Sept. 25, and Bill Stepien, the president’s campaign manager, who was with him at Tuesday’s debate.
But the rest of Mr. Trump’s family tested negative, as did Mr. Pence, Mr. Meadows, Secretary of State Mike Pompeo, Treasury Secretary Steven Mnuchin, Attorney General William P. Barr and other senior officials who are regularly in proximity to the president.
Former Vice President Joseph R. Biden Jr., the president’s Democratic challenger who was on the debate stage with Mr. Trump on Tuesday, tested negative on Friday. Mr. Biden said he sent his prayers for a speedy recovery while also implicitly faulting the president for a casual and even reckless approach to the virus.
“This is not a matter of politics,” Mr. Biden said at a gathering in Grand Rapids, Mich., while wearing a mask. “It is a bracing reminder for all of us that we must take this virus seriously. It is not going away. We must all do our part to be responsible. That means following the science, listening to experts.”
Mr. Trump by his own admission has played down the severity of the virus, repeatedly declaring that it would vanish on its own, pressuring schools, businesses and sports leagues to reopen, disputing the warnings of his own public health experts and questioning the effectiveness of face masks. He defied health guidelines by hosting campaign rallies and other events crowded with supporters who mostly did not wear masks or maintain social distance. Only hours before his own positive test, Mr. Trump insisted in a speech that “the end of the pandemic is in sight.”
No one could say for sure when the president was infected, but the White House medical unit was focused on his ceremony in the Rose Garden last Saturday where he announced his nomination of Judge Amy Coney Barrett for the Supreme Court, an event where many officials and guests mingled without masks and without keeping distance.
Several guests and reporters who were present or traveled with the president on Air Force One later that evening tested positive on Friday, including Senators Mike Lee of Utah and Thom Tillis of North Carolina, both Republicans; the Rev. John I. Jenkins, the president of University of Notre Dame; Kellyanne Conway, the president’s former counselor; and Michael D. Shear, a White House correspondent for The New York Times. Judge Barrett previously recovered from the coronavirus.
Mr. Trump is the latest 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. But Mr. Trump has repeatedly brushed off concerns about his health, telling advisers that the coronavirus is a roll of the dice.
While the virus is much deadlier than the ordinary flu, the vast majority of people infected by it recover, especially if there is no underlying condition, but the threat climbs with age. At 74, Mr. Trump is in the most vulnerable category, with the risk increased because of his weight, which is categorized as obese. Eight out of every 10 deaths attributed to the virus in the United States have been among those 65 and older.
Mr. Trump is aware of those numbers and long said that older Americans were more at risk. For all his public dismissal of the coronavirus, advisers said Mr. Trump has been haunted by the death of a New York friend from his business days, Stanley Chera, 78, who went into the hospital with the coronavirus and never came out.
Dr. David A. Nace, a geriatrics expert and the director of medical affairs at the University of Pittsburgh Medical Center’s network of 35 nursing facilities, said in an interview on Friday that people who do not wear masks are exposed to higher concentrations of the virus, which can worsen the course of the disease.
About 5 to 15 percent of men in their mid-70s die from the virus, Dr. Nace said, although Mr. Trump will obviously benefit from excellent medical care and from the increased knowledge about how to treat patients. “My big fear is that he probably had a greater exposure,” Dr. Nace said. “Right now, he’s doing fine, but we’re early in this, and if that’s the case, we really have to watch him in the next two weeks.”
Even assuming Mr. Trump recovers quickly, it could be weeks before he is able to return to a full public life, calling into question the future of his already-faltering campaign for a second term. Trailing Mr. Biden by a significant margin in most polls, the president had been trying to change the subject from the pandemic, a goal that may now prove even more elusive.
The Trump campaign canceled the president’s plans to attend rallies in Florida on Friday, Wisconsin on Saturday and Arizona on Monday, and likewise scrapped in-person events featuring Mr. Trump’s family. Mr. Pence, however, will return to the campaign trail to pick up the burden of making the administration’s case to voters as many have begun casting ballots.
Mr. Biden followed through on his campaign schedule for the day and plans to continue to, but Democratic officials said they were moving to take down television ads assailing the president for his handling of the pandemic, and the former vice president’s campaign manager emailed the staff warning against social media posts on Mr. Trump’s condition.
White House officials said Mr. Trump was well enough to work and he spoke with Senators Mitch McConnell of Kentucky, the Republican leader, and Lindsey Graham of South Carolina. “We’ve talked a number of times this morning,” Mr. Meadows said. “I got the five or six things that he had tasked me to do like I do every single morning, and he is certainly wanting to make sure that we stay engaged.”
If the illness were to become worse, the president could temporarily transfer his powers to Mr. Pence under the 25th Amendment with the transmission of letters to the speaker of the House and president pro tempore of the Senate and then reclaim them once he recovers.
Since the amendment was ratified in 1967, presidents have done so only three times. In 1985, President Ronald Reagan underwent a colonoscopy and briefly turned over power to Vice President George Bush, although he did not explicitly cite the amendment in doing so. President George W. Bush did invoke the amendment twice in temporarily turning over power to Vice President Dick Cheney during colonoscopies in 2002 and 2007.
At the White House, staff members were in various stages of shock and disbelief on Friday, unsure how to respond to a situation that may have been predictable but that many of them had never taken seriously. Some aides stayed home on Friday and others who for months have generally gone without masks in the West Wing in deference to a president who scorned them almost universally covered their faces.
There was rising frustration on the part of some aides late in the day that so little information was being released about the president’s health, in part because they worried it would stoke fears beyond the known facts. Some staff members described a rush for tests for themselves, with some told they could not get them.
Dr. Conley, the president’s physician, did not explain why Mr. Trump was taken to the hospital. In a statement released beforehand, he said that “the president remains fatigued but in good spirits.” He had more positive assessment of the first lady, saying that she “remains well with only a mild cough and headache.” The president, in his short video, said, “The first lady is doing very well.”
White House officials likewise did not explain why Mr. Trump went ahead with a fund-raising trip to New Jersey on Thursday even after learning that Ms. Hicks had tested positive for the virus. Mr. Meadows told reporters that the president’s entourage learned about her test result even as Marine One was lifting off from the White House to begin the trip to his golf club in Bedminster, N.J., and decided to leave some aides behind, but did not say why the trip was not canceled. “It was deemed safe,” said Kayleigh McEnany, the White House press secretary.
The experimental antibody treatment developed by Regeneron and administered to the president is one of the most promising candidates for a treatment. Initial test results indicate it can reduce the virus in the body and possibly shorten hospital stays. Although it has not been authorized by the Food and Drug Administration, the president’s medical staff reached out to Regeneron for permission to use it and the F.D.A. cleared it.
There is a long history of presidents falling seriously ill while in office, including some afflicted during epidemics. George Washington was feared close to death amid an influenza epidemic during his second year, while Woodrow Wilson became sick during Paris peace talks after World War I with what some specialists and historians believe was the influenza that ravaged the world from 1918 through 1920.
Four presidents have died in office of natural causes: William Henry Harrison, Zachary Taylor, Warren G. Harding and Franklin D. Roosevelt, while Wilson endured a debilitating stroke and Dwight D. Eisenhower had a heart attack in his first term and a stroke in his second. Four others were assassinated in office: Abraham Lincoln, James A. Garfield, William McKinley and John F. Kennedy.
But such health crises in the White House have been rarer in recent times. Since Reagan was shot in 1981, no president has been known to confront a life-threatening condition while in office.
Peter Baker reported from Washington, and Maggie Haberman from New York. Reporting was contributed by Annie Karni, Michael D. Shear, Sui-Lee Wee and Sheryl Gay Stolberg.