Donald Trump removed his mask seconds after returning to the White House on Monday after a three-night hospital stay for treatment for Covid-19.

The US president appeared not to care about infecting photographers or staff as he walked up the staircase of the White House South Portico, removed his surgical mask, and posed for pictures, at times giving a thumbs-up and others a salute. He was surrounded by the national flag.

His aides have been hit by a wave of infections as the pandemic – which has taken more than 200,000 American lives – further shadowed the election campaign. It is four weeks until polling day.

Leaving the the Walter Reed military hospital outside Washington earlier in the evening, he responded 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 in the November 3 election, was admitted to the hospital on Friday after being diagnosed with the disease caused by the novel coronavirus.

“Feeling really good!” he said on Twitter earlier. “Don’t be afraid of Covid. Don’t let it dominate your life. We have developed, under the Trump Administration, some really great drugs & knowledge. I feel better than I did 20 years ago!”

But despite attempts to project strength, he did not look well.

The disease has killed more than 1 million people worldwide and more than 209,000 in the United States alone – the highest death toll of any country.

Trump, 74, has not had a fever in more than 72 hours and his oxygen levels are normal, his medical team told reporters in front of the hospital. The doctors declined, however, to discuss any toll the disease could have on the president’s lungs or disclose when Trump last tested negative for the coronavirus.

The team added that the president had received supplemental oxygen twice in recent days.

“He may not entirely be out of the woods yet,” Dr Sean P Conley, the White House physician, said. “If we can get through to Monday with him remaining the same or improving, better yet, then we will all take that final, deep sigh of relief.”

But Conley said the medical team believed Trump was ready to leave the hospital, stressing he would have world-class medical care around the clock at the White House.

Conley said doctors were in “uncharted territory” because Trump had received certain therapies so early in the course of the illness.