US President Donald Trump has been discharged from hospital 72 hours after being treated for COVID-19, letting his American fan base know he will be “back on the campaign trail soon”.

A military helicopter arrived at the Walter Reed National Military Medical Centre in Bethesda, Maryland, at 9.15am (Australian time) on Tuesday to pick up the President and return him to the White House where he will continue medical treatment.

Wearing what appeared to be a white surgical mask, Mr Trump pumped his fist and gave a thumbs up as he walked down the steps of the medical centre, responding to a reporter’s question about how many people were infected at the White House by saying: “Thank you very much.”

The Republican president, running for re-election against Democrat Joe Biden on November 3, was admitted to the hospital on Friday after being diagnosed with the disease caused by the novel coronavirus.

Just after 9.30am, dressed in a suit, tie and mask, Mr Trump walked down the front steps of the military hospital, paused briefly for a quick fist-pump and got into a black SUV with a team of Secret Service agents.

He was then driven a short distance to Marine One, and just after 9.45am, the President was back in the air to reunite with First Lady Melania at the White House.

He landed less than 10 minutes later on the front lawn of the White House.

Tweet from @TeamTrump

Mr Trump’s medical team said he would receive his fourth dose of Remdesivir when he returned to the White House later on Tuesday.

In the latest briefing early on Monday (Australian time), personal physician Dr Sean Conley said the President had “met or exceeded all standard hospital discharge criteria”.

Mr Trump’s last fever was more than 72 hours ago and his oxygen levels were “all normal”, Dr Conley said.

“Though he may not entirely be out of the woods yet, the team and I agree that all our evaluations and, most importantly, his clinical status, support the President’s safe return home, where he will be surrounded by world-class medical care 24/7,” he said.

Tweet from @realDonaldTrump

Earlier on Tuesday (Australian time) Mr Trump told Americans not to fear the coronavirus and said he was “feeling really good”.

“Don’t be afraid of COVID. Don’t let it dominate your life,” he wrote on Twitter.

“I feel better than I did 20 years ago!”

Tweet from @realDonaldTrump

His announcement came shortly after it was revealed that White House press secretary Kayleigh McEnany and two of her deputies tested positive for COVID-19.

In a statement posted on Twitter, Ms McEnany said the White House medical unit did not list reporters, producers, or other members of the press as close contacts.

But sources told CNN that two of her deputies, Chad Gilmartin and Karoline Leavitt, had also contracted the coronavirus.

And there are concerns others will fall ill, after it was noted Ms McEnany had removed her mask to speak to journalists at recent briefings.

The press officer said she “definitively had no knowledge” about claims that Mr Trump’s adviser Hope Hicks was diagnosed with the virus before holding a press briefing on Friday. Just hours later, the President announced he and wife Melania had the coronavirus.

Ms McEnany is one of 11 of Mr Trump’s staffers or close contacts to test positive to COVID-19 so far.

• Read more: Here’s who of Trump’s friends have been infected 

With a leader who has treated face masks as optional and consistently downplayed the seriousness of the coronavirus – which has killed more than 200,000 Americans – it’s little wonder those in the White House inner circle are falling ill.

Despite the growing cluster, the White House medical team has remained “upbeat” to, they said, reflect Mr Trump’s own attitude.

Press Secretary Kayleigh McEnany with Donald Trump. Photo: AAP

-with AAP