US President Donald Trump will spend a "few days" at a military hospital after contracting Covid-19, the White House said, as the virus that has killed more than 205,000 Americans spread to the highest reaches of the US government.
Trump "remains fatigued," his doctor said. He was to depart the White House by helicopter late last night for Walter Reed National Military Medical Center.
The White House said the visit was precautionary and that he would work from the hospital's presidential suite, which is equipped to allow him to continue his official duties.
"President Trump remains in good spirits, has mild symptoms, and has been working throughout the day," said press secretary Kayleigh McEnany.
"Out of an abundance of caution, and at the recommendation of his physician and medical experts, the president will be working from the presidential offices at Walter Reed for the next few days."
Earlier, the White House said Trump had been injected with an experimental antibody cocktail by the White House physician.
The president's physician said in a memo that Trump received a dose of an experimental antibody cocktail by Regeneron that is in clinical trials. Navy Commander Dr. Sean Conley said Trump "remains fatigued but in good spirits" and that a team of experts was evaluating both the president and first lady.
The first lady, who is 50, has a "mild cough and headache," Conley reported, and the remainder of the first family, including the Trumps' son Barron, who lives at the White House, tested negative.
The revelation he has the virus came only a month before the election in a Trump tweet after he returned from a political fundraiser without telling the crowd he had been exposed to an aide with the disease.
Covid-19 has killed more than 205,000 Americans and one million-plus people worldwide.
First Lady Melania Trump also tested positive, the presi- dent said, and several others in the White House have too, prompting concern that the White House or even Trump himself might have spread the virus further.
Both Democratic presidential nominee Joe Biden and his running mate Kamala Harris have tested negative, their campaign said. Vice-president Mike Pence tested negative for the virus yesterday morning and "remains in good health", his spokesman said.
Mr Trump's Supreme Court nominee, Judge Amy Coney Barrett, who was with him and many others on Saturday and has been on Capitol Hill meeting with lawmakers, also tested negative, the White House said.
The president's diagnosis was sure to have a destabilising effect in Washington and around the world, raising questions about how far the virus has spread through the highest levels of the US government.
Hours before Mr Trump ann-ounced he had contracted the virus, the White House said a top aide who had travelled with him during the week had tested positive.
"Tonight, @FLOTUS and I tested positive for Covid-19. We will begin our quarantine and recovery process immediately," the president tweeted. "We will get through this TOGETHER!"
Chief of staff Mark Meadows tried yesterday to assure the public that Mr Trump was conducting business as usual, even as he confirmed that the White House knew Hope Hicks, the aide, had tested positive before the president attended a fundraiser in New Jersey on Thursday.
"In terms of Hope Hicks, we discovered that right as Marine One was taking off yesterday," said Mr Meadows.
Several staffers were pulled from the trip, but Mr Trump did not cancel, even after having been exposed to Ms Hicks.
Many White House and senior administration officials were undergoing tests yesterday, but the full scale of the outbreak around the president may not be known for some time as it can take days for an infection to be detectable.
Officials with the White House medical unit were trying to trace the president's contacts.
Mr Trump was considering how he might address the nation or otherwise communicate with the American people yesterday, an official said.
The president is 74-years-old and clinically obese, putting him at higher risk of serious complications from a virus that has infected more than seven million people in the US.
His physician said he and Mrs Trump, who is 50, "are both well at this time" and "plan to remain at home within the White House during their convalescence".
Mr Trump has been trying all year to convince the American public that the worst of the pandemic is behind them.
His illness, coming only weeks before the election, puts his participation in the second presidential debate, scheduled for October 15 in Miami, into doubt.
Mr Trump's handling of the pandemic has already been a major flashpoint in his race against Mr Biden, who spent much of the summer off the campaign trail, remaining at his home in Delaware, citing concern about the virus.
He has since resumed a more active campaign schedule, but with small, socially-distanced crowds.
He also regularly wears a mask in public, something Mr Trump mocked him for at Tuesday night's debate.
"I don't wear masks like him," the president said of Mr Biden. "Every time you see him, he's got a mask. He could be speaking 200 feet away from me, and he shows up with the biggest mask I've ever seen."
In a tweet yesterday, Mr Biden said he and his wife Jill "send our thoughts to President Trump and First Lady Melania Trump for a swift recovery. We will continue to pray for the health and safety of the president and his family".
World leaders offered the president and his family their best wishes as governments used the case as a reminder for citizens to wear masks and practice social-distancing measures.
Mr Trump's announcement came hours after he confirmed Ms Hicks had been diagnosed with the virus on Thursday.
She began feeling mild symptoms during the flight home from a rally in Minnesota on Wednesday evening, and was isolated from other passengers aboard the plane.
Mr Trump has consistently played down concerns about being personally vulnerable.
"I felt no vulnerability whatsoever," he told reporters in May.
Serious questions remain about why the president and his aides continued to go to work and travel after Ms Hicks became ill.
Mr Trump's social media director Dan Scavino and press secretary Kayleigh McEnany, who were supposed to join him on the trip to New Jersey, were replaced at the last minute.
However, Ms McEnany still briefed the press on Thursday morning and made no mention of Ms Hicks' suspected illness, raising anew concerns about White House transparency.
Mr Trump is far from the first world leader to test positive for the virus, which previously infected Brazilian president Jair Bolsonaro and British prime minister Boris Johnson, who spent a week in hospital, including three nights in intensive care.