"Through advances in treatment we have reduced the fatality rate by 85 per cent since just April," Mr Trump, 74, told the annual Al Smith dinner, held online this year due to the pandemic.
"We're on track to develop and distribute our vaccine before the end of the year, maybe substantially before. And I just want to say that the end of the pandemic is in sight," he added.
Just hours later, it was announced that he and the first lady, 50, had tested positive for coronavirus, news that is likely to throw the race for the White House into chaos, with just over a month to go before November's poll.
The couple has begun quarantining and will remain at the White House throughout their period of self-isolation, with the president saying he and the first lady "will get through this TOGETHER!”
Sean P. Conley, Mr Trump's doctor, said "the President and First Lady are both well at this time". He added that the commander-in-chief would continue to carry out his duties "without disruption".
Mr Conley did not say whether the president had been experiencing any symptoms , either before or after testing positive for coronavirus , which has claimed some 208,000 US lives.
Sources would not confirm to the New York Times whether the president had experienced any symptoms. People at the White House noticed that his voice sounded "raspy" on Thursday, the publication reported, although that could have been the result of a campaign rally in Minnesota the previous night.
As someone in his 70s and overweight, the president could be considered in a number of "high risk" coronavirus categories. According to reports, he also has a poor diet and does not exercise. Covid-19 fatality rates are highest among the elderly and those with underlying health conditions.
It is not clear at this stage where the president might have picked up the infection, although he was in close contact with aide Hope Hicks, who tested positive earlier on Thursday.
In the event that Mr Trump is incapacitated by sickness, the duties of the president would fall to vice president Mike Pence. "Karen and I send our love and prayers to our dear friends President @realDonaldTrump and @FLOTUS Melania Trump," the VP said on Friday morning.
"We join millions across America praying for their full and swift recovery. God bless you President Trump & our wonderful First Lady Melania.
Democratic challeneger, Joe Biden, 77, has yet to respond to the news that the president has tested positive. The pair came into close contact on Tuesday night during the first presidential debate.
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