REUTERS

U.S. President Trump left Walter Reed Medical Center on Monday, hours after the medical team treating him for COVID-19 cautioned that he's "not out of the woods yet."

He got back to the White House, where he gave a thumbs up before walking inside, taking off his mask as he did, CBS News reported.

Then Trump tweeted a minute-long video from the balcony, saying he'd "learned so much about coronavirus" and believes he might be immune to it. "One thing that's for certain: Don't let it dominate you," he said of COVID-19. "Don't be afraid of it. You're going to beat it."

The president's stance rang alarms among many medical experts, who said he should have stressed precautions Americans should take to try to avoid getting the coronavirus.

Earlier Monday, Dr. Sean Conley, the White House physician, told reporters Donald Trump will be "surrounded by world-class medical care, 24/7" at the White House.

Read alsoZelensky wishes Trump, First Lady "fast and full recovery" from COVID-19He's being treated with dexamethasone, a powerful steroid recommended for use in severe cases of COVID-19. The drug can carry serious psychological side effects, but Conley said the president hasn't exhibited any of them. He repeatedly declined to provide specifics about the president's lung condition or the last time Mr. Trump tested negative for the virus, citing federal privacy laws.

Meanwhile, the outbreak at the White House continued as more staff members tested positive. Press secretary Kayleigh McEnany said Monday that she'd tested positive for COVID-19, and sources with knowledge of the matter confirmed to CBS News that one of her deputies had tested positive, as well.

"It is inexplainable that the President of the United States, who is actively shedding virus in millions of particles, would walk into that building with an enormous number of staff, unmasked," said Dr. Jonathan Reiner, a professor at George Washington University School of Medicine, according to CNN.

The U.S. president, CNN adds, has a pressing political interest in proving that he is better 28 days from an election in which he is trailing Joe Biden. His campaign said Monday that he fully planned to debate the Democratic nominee in their second head-to-head clash – a town hall event with members of the public in Miami next week.