US President Donald Trump has left hospital, three days after being admitted with Covid-19, vowing to be back on the campaign trail soon.

He flew for the short trip back to the White House on the presidential helicopter Marine One.

"Feeling really good!" Mr Trump tweeted earlier. "Don't be afraid of Covid. Don't let it dominate your life."

More than 7.4 million cases of Covid-19 have been recorded in the US. The virus has killed nearly 210,000 Americans.

President Trump has returned to the White House on Monday, on his fourth day at Walter Reed National Military Medical Center, though his doctor said he might not be "out of the woods" yet.

The president walked from Marine One into the White House residence, and up to the balcony, where he removed his mask.

The president announced his expected departure from the military hospital earlier with a tweet. "Don't be afraid of COVID," he wrote. "Don't let it dominate your life."

President Trump was discharged from Walter Reed National Military Medical Center and returned to the White House on Monday evening to continue his fight against the novel coronavirus, after his medical team warned that he “may not entirely be out of the woods yet.”

Dressed in a navy suit and tie and wearing a face mask, Trump walked out of Walter Reed on his own. Upon walking out the doors of the hospital, he made a low fist pump and gave a thumbs up to the press as he got into a black SUV to head to Marine One.

White House chief of staff Mark Meadows said President Donald Trump's condition "continued to improve" Sunday night and that he may still leave the hospital Monday as he battles a COVID-19 infection.

John Roberts of Fox News tweeted the update from Meadows:

"URGENT: From WH COS Mark Meadows to Fox News: 'Spoke to the President this morning. He continued to improve over night and is ready to get back to a normal working schedule. He will meet with his doctors and nurses this morning to make further assessments of his progress.

President Donald Trump and the team of doctors treating him for the coronavirus will decide Monday whether to discharge him from Walter Reed Medical Center, NBC News reported.

Trump’s possible departure could send a signal that his health is improving following his diagnosis. But the move is bound to breed skepticism among those who have criticized administration officials for a lack of transparency on the president’s condition, particularly in light of the numerous treatments he is known to have taken.

They say he is in a particularly vulnerable window for covid-19 patients and should be watched closely while taking an unusual combination of drugs.

The assertion by President Trump’s doctors that he could be discharged from the hospital as early as Monday astonished outside infectious-disease experts, who said he remains in a dangerous period of vulnerability when some covid-19 patients decline precipitously and require urgent intervention.