President Donald Trump tried to allay supporters' concerns about his health on Saturday evening by releasing a four-minute video saying he felt much better after treatment following his positive test for COVID-19, and that doctors at the Walter Reed Medical Center were "working hard to get me all the way back."

In the video, posted on Trump's Twitter account, the president added that his wife Melania was "really handling it very nicely," after her own diagnosis with the virus.

The video came after a day of mixed messages from official channels about the president's health, as well as confusion about when exactly he had been diagnosed with the novel coronavirus.

The president's physician, Dr. Sean Conley, told the press outside the Walter Reed military hospital on Saturday morning that the 74-year-old's symptoms had abated, that his fever had gone down and that he was not being given extra oxygen.

But Conley refused to say whether the president had ever needed supplemental oxygen, despite repeated questioning, and declined to say how high a fever Trump had been running before it came back down to a normal range.

But Conley's optimistic account was contradicted within minutes by a press pool reporter, who passed on a statement from White House chief-of-staff Mark Meadows saying that Trump's "vitals over the last 24 hours were very concerning and the next 48 hours will be critical in terms of his care."

"We're still not on a clear path yet to a full recovery," Meadows said.

There had also been numerous reports that Trump had indeed been given oxygen at the White House, before the decision was made to move him to the hospital.

The mixed messages were not helped by another statement made by Conley during his press briefing, when he said that Trump had begun exhibiting "clinical indications'' of COVID-19 on Thursday afternoon, earlier than previously known.

Conley also said "we're 72 hours into [Trump's] diagnosis," which would have meant that the president had carrying out his regular duties for more than a day before making his test result public.

The White House press team quickly clarified that Conley had misspoken, and had meant to say "day three," since he had tested positive on Thursday evening.

bk/aw (dpa, AFP, AP)