WASHINGTON — US President Donald Trump was on Wednesday (Oct 8) back at work in the Oval Office just six days after testing Covid-19 positive, despite warnings that his return could put others at risk.

The behaviour of the president — who has faced fierce criticism for his handling of the outbreak — is under scrutiny as the number of positive cases climbs among people working at the White House.

After contradictory statements whether the US President was back at work on Tuesday, a senior administration official said that Mr Trump was present Wednesday with an "extremely limited" number of staff in his office.

Mr Trump, who was hospitalised Friday with the virus that has killed over 210,000 in the US, arrived by an outside door to avoid passing through the crowded corridors of his residence, the official said.

"Was just briefed on Hurricane Delta," the US President tweeted, eager to project his return as a personal triumph over the disease as he trails badly in polls against Democratic challenger Joe Biden.

Mr Trump's illness, like his dismissive stance on the virus, has fueled multiple controversies, including his made-for-television exit from the hospital on Monday.

Just after stepping off a helicopter at the White House, he climbed the stairs of his residence and pulled off his face mask — a tool against the virus that he has frequently downplayed.

"Don't let (Covid-19) dominate you. Don't be afraid of it," he urged Americans in his homecoming speech, despite the US having the largest total number of coronavirus infections and deaths in the world.

'WACKO FOR YEARS'

By Wednesday, doctors reported the president had been free of Covid-19 symptoms for 24 hours and has not had a fever in four days.

"The president this morning says 'I feel great,'" doctor Sean Conley said in a brief update. 

In an apparent attempt to provide greater clarity over how the disease has progressed, the update also detailed that Covid antibodies were found in Mr Trump's blood tests on Monday.

Dr Florian Krammer, professor at Icahn School of Medicine in New York, said those results don't mean much at this stage.

"It could well be that the majority of what is detected came from the transfusion," he said referring to the experimental antibody treatment Mr Trump got Friday.

Mr Trump has vowed to return to campaigning shortly and to participate in the second presidential debate against Mr Biden in Miami on Oct 15.

As Mr Trump seeks to revive his reelection campaign in the face of weak polling data just four weeks away from the Nov 3 election, he labelled Mr Biden "a wacko".

Latest polls forecast a clear victory for Mr Biden, with CNN giving the Democrat a national advantage of 57 per cent to 41 per cent among likely voters, and women voters going 66 to 32 per cent in his favour.

"He's been a wacko for years, and everyone knows it," Mr Trump tweeted. "Notice how all of the bad things, like his very low IQ, are no longer reported? Fake News!"

Mr Biden traded blows with Mr Trump in last week's chaotic debate, but the former US Vice President has also appealed to a broad-based yearning for calm.