Manager Craig Counsell did not specify the reason for Burnes going on the IL and said he couldn't comment on the situation when asked directly whether the Brewers ace had tested positive for COVID-19.
"Corbin is on the injured list," Counsell said Thursday afternoon. "I can't discuss it."
MLB teams are not allowed to disclose the names of any player who tests positive for the coronavirus unless the player gives his authorization.
Burnes, 26, is 2-2 with a 1.53 ERA this season. He has yet to issue a walk while striking out 49 batters, two shy of the record for most strikeouts to start a season without a walk. That's held by Dodgers closer Kenley Jansen, who would have witnessed Burnes going after that mark on Sunday had Burnes pitched.
"He's done historic stuff so missing him for any period of time hurts," president of baseball operations David Stearns said. "I feel bad for Corbin. He's worked really hard to get to this point, to have this level of success and now he has to press pause. Clearly we want him back as soon as we possibly can get him."
The Brewers won't name a replacement for Burnes until after Saturday's game against the Dodgers. Burnes joins outfielders Christian Yelich (back) and Lorenzo Cain (quad) on the injured list, as the first-place team in the NL Central has had an inordinate number of ailments to begin the season.
"We're getting hit with injuries," Counsell said. "There's no reason to get upset about this. We have to deal with it. We're working on getting guys healthy. Not one of these injuries is a long-term thing. We will get these players back."
Yelich and Cain are getting close to returning, although Yelich was ruled out of the games Friday and Saturday.
"It's all good news," Counsell said. "They're all out on the field going at fairly close to game speed."