US President Donald Trump said on Friday that he and first lady Melania have tested positive for the coronavirus — just a month before the presidential election.

"We will begin our quarantine and recovery process immediately. We will get through this TOGETHER!" Trump tweeted early Friday.

Melania, through her official account, said she and Trump were quarantining at home after testing positive for Covid-19 "as too many Americans have done this year".

"We are feeling good and I have postponed all upcoming engagements," she said.

In a memorandum, the president’s physician said that Trump and first lady “are both well at this time” and “plan to remain at home within the White House during their convalescence”.

“Rest assured, I expect the president to continue carrying out his duties without disruption while recovering,” he added.

Prime Minister Imran Khan in a message on Twitter wished Trump and Melania a "speedy recovery" from the virus.

Democratic presidential candidate Joe Biden also wished Trump and Melania a swift recovery.

"Jill and I 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," he said on Twitter.

Trump’s positive test comes just hours after the White House announced that senior aide Hope Hicks came down with the virus after traveling with the president several times this week. Trump was last seen by reporters returning to the White House on Thursday evening and looked to be in good health. Trump is 74 years old, putting him at higher risk of serious complications from a virus that has now killed more than 205,000 people across US.

The diagnosis, just weeks before the November 3 election, marks a major blow for a president who has been trying desperately to convince the American public that the worst of the pandemic is behind them, despite a growing nationwide death toll of more than 205,000 and seven million confirmed infections. And it stands as the most serious known public health scare encountered by any sitting American president in recent history.

Trump had consistently played down concerns about being personally vulnerable to contracting Covid-19, even after White House staff and allies were exposed and sickened.

“I felt no vulnerability whatsoever,” he said told reporters back in May.

He has instead encouraged governors to reopen their states and tried to focus the nation’s attention on efforts to revive the economy — not a growing death toll — as he seeks another four-year term.

Trump’s handling of the pandemic has become a major flashpoint in his race against Democrat Joe Biden, who spent much of the summer off the campaign trail and at his home in Delaware. Biden has since resumed a more active campaign schedule, but with small, socially distanced crowds because of the virus. Biden also regularly wears a mask in public, something Trump mocked him for at the first debate.

“I don’t wear masks like him,” Trump said of 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.”

Questionable health, safety protocols

Since the early days of the pandemic, experts have questioned the health and safety protocols at the White House and asked why more wasn’t being done to protect the commander in chief. Trump continued to shake hands with visitors long after public health officials were warning against it and he initially resisted being tested. He has been reluctant to practice his own administration’s social distancing guidelines for fear of looking weak, including refusing under almost all circumstances to wear a mask in public.

Trump is not the only major world leader known to have contracted the virus. British Prime Minister Boris Johnson spent a week in the hospital, including three nights in intensive care, where he was given oxygen and watched around the clock by medical workers. German Chancellor Angela Merkel self-isolated after a doctor who gave her a vaccination tested positive for the virus, and Canadian Prime Minister Justin Trudeau worked from home after his wife fell ill.

While there is currently no evidence that Trump is seriously ill, the positive test also raises questions about what would happen if he were to become incapacitated due to illness. The US constitution’s 25th Amendment spells out the procedures under which a president can declare themselves “unable to discharge the powers and duties” of the presidency. If he were to make that call, Trump would transmit a written note to the Senate president pro tempore, Republican Senator Chuck Grassley of Iowa, and House Speaker Nancy Pelosi, D-Calif. Pence would serve as acting president until Trump transmitted “a written declaration to the contrary”.

The vice president and a majority of either the US cabinet or another body established by law, can also declare the president unable to discharge the powers and duties of his office, in which case Pence would “immediately assume the powers and duties of the office as Acting President” until Trump could provide a written declaration to the contrary.

Covid-19 and the White House

Senior staff have been tested for Covid-19 daily since two people who work at the White House complex tested positive in early May, prompting the White House to step up precautions. Everyone who comes into contact with the president also receives a quick-result test.

The White House got its first Covid-19 scare in early March when at least three people who later tested positive came in close proximity to the president at his private Florida club. That included members of the Brazilian president’s delegation, including the Brazilian chargé d’affaires, who sat at Trump’s dinner table.

In mid-March, as the virus continued to spread across the country, the White House began taking the temperature of everyone entering the White House complex, and in April, it began administering rapid Covid-19 tests to all those in close proximity to the president, with staffers being tested about once a week. The frequent tests gave some staff the false impression the complex was safe from the virus, and few, as a result, followed recommended safety protocols, including wearing masks.

But then the bubble broke.

On May 7, the White House announced that a member of the military serving as one of the president’s personal valets tested positive for the virus, followed a day later by a positive diagnosis for US Vice President Mike Pence’s press secretary.

Even then, Trump said he was “not worried” about the virus spreading in the White House. But officials again stepped up safety protocols for the complex, directing everyone entering the West Wing to wear a mask.

“I think it’s very well contained, actually,” Trump told reporters on May 11.

But by June, concerns at the White House had dissipated once again, with few staffers bothering with masks even as more and more people tested positive for the virus, including campaign staffers preparing for a Tulsa rally and Secret Service agents.

On July 3, Kimberly Guilfoyle, who is dating Trump’s eldest son, Donald Trump Jr, tested positive in South Dakota before an Independence Day fireworks show at Mount Rushmore. Guilfoyle, a former Fox News personality who works for Trump’s campaign, had not flown on Air Force One and had not been in direct contact with the president, though she had had contact with numerous top GOP officials.

In July, Trump’s national security adviser, Robert O’Brien, tested positive.