The pandemic has killed more than 65,000 people in Brazil.
The right-wing populist told a group of television reporters that he had developed symptoms at the weekend.
"It started on Sunday with a certain malaise and became worse throughout the day on Monday, feeling poorly, exhaustion, a bit of muscle ache, fever hit 38 (degrees Celsius)," he said.
Finishing the interview, he stepped back and removed his mask to reveal a smile, adding: "You can see from my face that I'm well and I'm calm."
