President Donald Trump should not be discharged from the hospital too soon because Covid-19 can be "very stealthy" and infected patients can "suddenly crash," a medical expert said Monday.
"It is a little bit confusing, but by and large, the president looks pretty good," said Dr. William Schaffner, a professor of medicine at the Vanderbilt University School of Medicine. "So far so good, and we have high hopes for his complete and rapid recovery."
"But that said, he's still in a dangerous position. He is 74 years old, he is overweight, he is male. All of those things put him in a more severe category potentially," Schaffner told CNBC's "Street Signs Asia."
The coronavirus can be debilitating and is sometimes fatal. The disease has so far infected more than 35 million people worldwide, killing more than 1 million, according to data compiled by the Johns Hopkins University.
Trump announced on Friday that he and first lady Melania Trump tested positive for the coronavirus. He was admitted to Walter Reed National Military Medical Center later that day and has been receiving treatment there.
His physician, Dr. Sean Conley, said the president had a high fever late Friday morning, and his oxygen saturation level dropped below healthy levels twice — on Friday and Saturday.
He also said Trump has been administered dexamethasone, a steroid that has been used to treat severe cases of Covid-19, and added that the president could be discharged as early as Monday.
Schaffner said he hopes Trump stays in the hospital for a few more days "under the 24-hour-a-day, watchful attention of the staff."
"We know this infection can be very stealthy and … kind of fake you out, because you can do well for several days and then suddenly crash," he said.
If things go sour when he is back in the White House or an emergency happens and they need to take him back to Walter Reed, it would not be good for Trump, he added. "That would not be a good idea. Let's be conservative and take it a day at a time."
Patients are usually declared free from the coronavirus if their symptoms have been resolved and it has been 10 days since the onset of symptoms or the positive test, Schaffner said. "Under that sort of formula, (Trump) still has a few more days to go."
He said it sounds like Trump developed symptoms on Wednesday evening, and may have been infected a few days earlier. The president's doctors appear to be treating him for pneumonia, a more severe form of Covid-19, said Schaffner.
"The virus builds up in your body before it starts to make you ill, so he could have been infected for quite some days … and then become infectious let's say Tuesday, maybe even Monday of last week," he said. "Potentially, the number of people who contacted him without precautions, without 6-foot distancing, could be very large indeed."
Trump was regularly tested for the virus, but Schaffner said the White House uses a test that sometimes produces false negatives.
Campaign manager Bill Stepien, Republican National Committee Chair Ronna McDaniel and several Republican senators have tested positive for the virus. Many of them either met the president or attended events at the White House more than a week ago. Vice President Mike Pence and second lady Karen Pence have returned with negative tests.
— CNBC's Emma Newburger and Tucker Higgins contributed to this report.