The Bulls were hoping either player's health would approve ahead of their win-or-go-home game in Milwaukee, but they downgraded both guards on their injury report Wednesday morning.
The Bucks lead the first-round series 3-1. Only 13 teams in NBA history have overcome a 3-1 deficit, and the Bulls' path to an unlikely comeback becomes more difficult without their starting backcourt available.
LaVine entered the COVID-19 health and safety protocols just before the team's practice Tuesday after he woke up experiencing symptoms earlier in the morning. It's the third time in the past 12 months and the second time this season he has landed in the league's protocols.
Caruso entered the concussion protocol during the second half of Sunday's Game 4 after he got hit in the face by an inadvertent elbow from Jevon Carter. Caruso left the game with a bloody nose and then started experiencing concussion symptoms.
Bulls coach Billy Donovan said in his Wednesday pregame availability that Caruso has a "pretty significant headache'' and that LaVine is feeling "pretty sick.''
LaVine is averaging 19.3 points, 5.3 rebounds and 6.0 assists in four postseason games against the Bucks. Caruso is averaging 6.3 points, 4.3 assists and 1.3 steals in the series while serving as the team's defensive anchor.
"It's part of sports," Bulls center Nikola Vucevic said after practice Tuesday. "If you look out throughout the NBA, I'm sure a lot of teams have gone through a lot of different ups and downs and injuries and COVID stuff. So you just have to deal with it.
"At no point did we feel sorry for ourselves or we will feel sorry for ourselves. It is what it is. It's unfortunate, but mainly for those guys that want to be out there with us and compete and they can't, they have to miss time. It's unfortunate mainly for them. For us, we just have to go out there and compete. It's an opportunity for somebody else to do it."
The Associated Press contributed to this report.