Donald Trump is hospitalised after being diagnosed with Covid

US President Donald Trump has appeared in public for the first time since being stricken by Covid, boarding his Marine One helicopter for a flight to a military hospital.

Mr Trump, 74, walked out of the White House and gave a thumbs-up but did not speak.

Members of the aircrew, Secret Service agents and White House staff wore face coverings to protect themselves from the president onboard the helicopter.

The White House said the visit of a few days to Walter Reed National Military Medical Center was precautionary and that Trump would continue to work from the hospital's presidential suite, which is equipped to allow him to keep up 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 on Friday, the White House said Mr Trump had been injected with an experimental antibody cocktail by the White House physician.

First lady Melania Trump also tested positive, the president said, and several others in the White House have, too, prompting concern that the White House or even Mr Trump himself might have spread the virus further.

Mr Trump has spent much of the year downplaying the threat of the virus, rarely wearing a protective mask and urging states and cities to "reopen" and reduce or eliminate shutdown rules.

The president's physician said in a memo on Friday that Mr Trump received a dose of an experimental antibody cocktail by Regeneron that is in clinical trials.

The first lady, 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.

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 on Friday and "remains in good health," his spokesman said.

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Mr Trump'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 announced he had contracted the virus, the White House said a top aide who had travelled with him during the week had tested positive.

Many White House and senior administration officials were undergoing tests on Friday, 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 by a test.

Officials with the White House Medical Unit were tracing the president's contacts.

Mr Trump's re-election campaign said it was putting on hold all events featuring Trump and members of his family but that Pence would resume campaigning since he tested negative.

Mr Trump has been trying all year to convince the American public that the worst of the pandemic is behind them.

His 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 and at his home in Delaware citing concern about the virus.

World leaders offered the president and first family their best wishes after their diagnosis, as governments used their case as a reminder for their citizens to wear masks and practice social distancing measures.

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