“This is insanity,” said Dr James P Phillips, an attending physician at Walter Reed, where Mr Trump has been treated since Friday evening.
“Every single person in the vehicle during that completely unnecessary Presidential ‘drive-by’ just now has to be quarantined for 14 days. They might get sick. They may die.”
“For political theater,” the doctor added on Twitter. “Commanded by Trump to put their lives at risk for theater.”
Hours earlier, Mr Trump’s medical team reported that his blood oxygen level dropped suddenly twice in recent days and that they gave him a steroid typically only recommended for the very sick.
Still, the doctors said Mr Trump’s health is improving and that he could be discharged as early as Monday.
“This is an important day as the president continues to improve and is ready to get back to a normal work schedule,” White House chief of staff Mark Meadows told Fox News on Monday.
He said the determination on whether Mr Trump would leave the hospital will not be made until later in the day after the president is evaluated by his medical team, but that Mr Trump was “optimistic” he could be released Monday.
Meanwhile, White House press secretary Kayleigh McEnany said she has tested positive for Covid-19.
Ms McEnany said in a statement that she tested positive on Monday morning and is experiencing no symptoms at this time.
She spoke briefly with reporters on Sunday evening, but says that no members of the White House press corps spent enough time around her to be considered close contacts.
She said that she is beginning the quarantine process and “will continue working on behalf of the American People remotely.”
With one month until election day in the US, Mr Trump was eager to project strength despite his illness.
The still-infectious president surprised supporters who had gathered outside Walter Reed National Military Medical Centre, driving by in a black vehicle with the windows rolled up.
Secret Service agents inside the vehicle could be seen in masks and other protective gear.
The move capped a weekend of contradictions that fuelled confusion about Mr Trump’s health, which has imperilled the leadership of the US government and upended the final stages of the presidential campaign.
While Mr Trump’s physician offered a rosy prognosis on his condition, his briefings lacked basic information, including the findings of lung scans, or were quickly muddled by more serious assessments of the president’s health by other officials.
In a short video released by the White House on Sunday, Mr Trump insisted he understood the gravity of the moment.
White House spokesman Judd Deere said Mr Trump’s trip outside the hospital “was cleared by the medical team as safe to do”.
He added that precautions were taken, including using personal protective equipment, to protect Mr Trump as well as White House officials and Secret Service agents.
Joe Biden’s campaign, meanwhile, said the Democratic presidential nominee again tested negative for coronavirus on Sunday.
The results come five days after Mr Biden spent more than 90 minutes on the debate stage with Mr Trump.
Mr Biden, who has taken a far more cautious approach to in-person events, had two negative tests on Friday.
The White House has refused to say when Mr Trump last tested negative and whether he was tested before the debate, but the Cleveland Clinic, which co-hosted the event, said that Mr Trump’s team certified the day of the debate that he and everyone who accompanied him in the debate hall had received a negative Covid-19 test.
For his part, Mr Trump still faces questions about his health.
His doctors sidestepped questions on Sunday about exactly when Mr Trump’s blood oxygen dropped — an episode they neglected to mention in multiple statements the day before — or whether lung scans showed any damage.
Pressed about conflicting information he and the White House released on Saturday, Navy Commander Dr Sean Conley acknowledged that he had tried to present a sunnier description of the president’s condition.
“I was trying to reflect the upbeat attitude that the team, the president, that his course of illness has had. Didn’t want to give any information that might steer the course of illness in another direction,” Dr Conley said. “And in doing so, you know, it came off that we were trying to hide something, which wasn’t necessarily true. The fact of the matter is that he’s doing really well.”
Medical experts said Dr Conley’s revelations were hard to square with his positive assessment and talk of a discharge.
“There’s a little bit of a disconnect,” said Dr Steven Shapiro, chief medical and scientific officer at the University of Pittsburgh Medical Centre.
According to CDC (Centres for Disease Control and Prevention) guidelines, “In general, transport and movement of a patient with suspected or confirmed SARS-CoV-2 infection outside of their room should be limited to medically essential purposes.”
Even before Mr Trump’s motorcade outing on Sunday, some Secret Service agents have expressed concern about the lackadaisical attitude toward masks and social distancing inside the White House, but there is not much they can do, according to agents and officials who spoke to The Associated Press.
This close to the election, thousands of agents are engaged on protective duty so they can be subbed out quickly should someone test positive.
The disclosures about Mr Trump’s oxygen levels and steroid treatment suggested the president is enduring more than a mild case of Covid-19.
Blood oxygen saturation is a key health marker for Covid-19 patients. A normal reading is between 95 and 100. Dr Conley said the president had a “high fever” and a blood oxygen level below 94% on Friday and during “another episode” on Saturday.
He was evasive about the timing of Mr Trump oxygen drops. (“It was over the course of the day, yeah, yesterday morning,” he said) and asked whether Mr Trump’s level had dropped below 90%, into concerning territory. (“We don’t have any recordings here on that.”)
But he revealed that Mr Trump was given a dose of the steroid dexamethasone in response.
At the time of the briefing, Mr Trump’s blood oxygen level was 98% — within normal rage, Mr Trump’s medical team said.
Signs of pneumonia or other lung damage could be detected in scans before a patient feels short of breath, but the president’s doctors declined to say what those scans have revealed.
“There’s some expected findings, but nothing of any major clinical concern,” Dr Conley said. He declined to outline those “expected findings”.
Asked about Dr Conley’s lack of transparency, White House aide Alyssa Farah suggested the doctors were speaking as much to the president as to the American public, “when you’re treating a patient, you want to project confidence, you want to lift their spirits, and that was the intent”.
In all, nearly 7.4 million people have been infected in the United States.
First lady Melania Trump has remained at the White House as she recovers from her own bout with the virus.
