President did not disclose 1st positive test, sources say
The president had already tested positive Thursday when he appeared on Fox News.
President Donald Trump's condition is continuing to improve as he fights a coronavirus infection, doctors say, and he may be able to leave Walter Reed Medical Center as early as Monday -- even as details emerge that the president allegedly initially tested positive for COVID-19 earlier than he acknowledged.
Doctors also reported that Trump, over the course of exhibiting coronavirus symptoms, had earlier experienced two episodes of "transient drops" in his oxygen saturation.
Yet the president was feeling well enough Sunday evening to briefly leave Walter Reed for a surprise drive-by, waving to supporters outside the hospital.
Meanwhile, numerous questions remain about how many people at the highest levels of government had been exposed to the virus after a week of events involving the president where social distancing and mask-wearing were lax in the White House and elsewhere.
Sunday's headlines:
AG Bill Barr tests negative, cancels some in person events
A spokeswoman for the Department of Justice told reporters on Sunday that Attorney General Bill Barr took "two rapid tests and one pcr test since Friday morning." All of the tests came back negative, according to DOJ spokeswoman Kerri Kupec.
"Out of an abundance of caution, he went to the department for only one meeting on Friday, stayed home this weekend other than getting tested, and will stay home tomorrow," she said.
Barr attended the Sept. 26 event at the White House where President Trump announced Judge Amy Coney Barrett as his Supreme Court Justice nominee.
Several Trump administration officials who contracted the virus last week, including Kellyanne Conway and former Gov. Chris Christie, attended the event and were not wearing masks during the outdoor ceremony.
Barr was photographed talking with Conway and not wearing a mask during the event.
-ABC News' Alexander Mallin
Independent voter reacts to Trump diagnosis, activities
ABC News spoke to one registered independent about his reaction to Trump testing positive and his activities leading up to the positive test result.
Rob Gorski, a former EMT and single father of three sons with autism in Akron, Ohio, said he was "very angry" that Trump "so willingly put so many people in harms way after knowing he'd been directly exposed to COVID-19."
"Trump and the others in the White House may do just fine, and I hope they do recover because no one deserves to die like that. But what about everyone else who they infected? They may not recover and they may have been doing everything right. They don't deserve that," he said.
ABC News Live Prime spoke with Gorski and three other families of special needs kids about how they are surviving the pandemic and back-to-school season.
-ABC News' Devin Dwyer
More on steroid treatment given to Trump
Doctors treating President Trump announced that he has been given the steroid Dexamethasone to combat symptoms of the coronavirus.
Dexamethasone, a steroid treatment, is seeing positive results in some patients.
A study in the United kingdom in June found that dexamethasone increased survival in severely ill COVID-19 patients who needed help breathing.
Trump's condition is improving, doctors say, but he did have two episodes where his oxygen levels dropped.
Prescribing dexamethasone for President Trump may be appropriate considering he received oxygen at some point during his illness.
"It's a borderline indication within the physicians prerogative," said Dr. William Schaffner, professor of preventative medicine in the Department of Health Policy as well as professor of medicine in the Division of Infectious Diseases at Vanderbilt University School of Medicine in Nashville, Tennessee.
Although the U.K. study appeared promising, dexamethasone only was demonstrated to help patients who have severe COVID-19 and need help breathing, through ventilation or oxygen assistance. The steroid treatment has not been proven to help people with a more mild COVID-19 illness, which accounts for most cases.
In fact, it may not be safe to use in patients with mild illness. In the U.K. study, dexamethasone "non-significantly increases death if used in milder patients with COVID-19," said Dr. Todd Ellerin, director of Infectious Diseases at South Shore Health. He warned that for patients with milder COVID-19 illness "the risks of the medication likely outweigh the benefits."
-ABC News' Sony Salzman contributed to this report
Masks mandatory at White House for NSC staff
White House national security adviser Robert O'Brien while speaking to reporters at the White House on Sunday announced that mask wearing is now mandatory for National Security Council staff.
"We made mask wearing mandatory for National Security Council staff," O'Brien said.
Mask wearing was previously voluntary.
-ABC News' Elizabeth K. Thomas