OWINGS MILLS, Md. -- Baltimore Ravens quarterback Lamar Jackson has proved to be extremely durable despite taking more hits than any other quarterback. It's the repeated battles with illness that have given him the most problems.

Jackson missed practice on Thursday, marking the fourth time this season that he has been sidelined because he has been sick.

Ravens offensive coordinator Greg Roman said Thursday that he didn't have a complete update on Jackson's status.

"I think he's feeling better," Roman said.

Ravens coach John Harbaugh said Wednesday that Jackson's illness is not COVID-related. The AFC North-leading Ravens (6-3) play at the Chicago Bears (3-6) on Sunday.

Jackson has held up strong during his four-year NFL career despite taking 668 hits (115 more than any other quarterback) since taking over as the Ravens starter midway through the 2018 season. He has missed only two games, sitting out the 2019 season finale because Baltimore had already secured the No. 1 seed and then being held out of a Week 12 game last season after testing positive for COVID-19.

But it's been a challenge to stay on the practice field for Jackson. He has missed a total of six practices in the first 11 weeks of this season, and only two of those absences were because of injury (sore back).

Without Jackson, backup quarterback Tyler Huntley has been running the first-team offense.

Jackson is in the midst of another MVP-like season. He ranks eighth in the NFL in passing (2,447 yards) and seventh in rushing (639).

Not having Jackson for consecutive practices just adds to the challenge of a Ravens offense looking to get back on track. In Baltimore's last game (a 22-10 loss at Miami on Nov. 11), Jackson had his impressive scoring streak -- 45 straight regular-season starts with at least 14 points -- come to an end. It was the longest such streak to start a career since 1950, according to the Elias Sports Bureau.

Ravens center Bradley Bozeman, who returned Thursday after missing one day with an illness, isn't concerned about the rhythm of the offense when Jackson is unable to practice.

"I don't really think it's that big of a deal," Ravens center Bradley Bozeman said of Jackson's absences. "I know Lamar is doing his things at home that he needs to do. He's watching plays. He's getting everything right at home. When he comes back in, he's not going to miss a step. Week in and week out, he's continued to build on that and step up to the plate when he needs to. I don't see that being an issue."

Two of Jackson's top wide receivers -- Marquise Brown (thigh) and Rashod Bateman (undisclosed) -- also did not practice Thursday. It's the second straight day that Brown didn't practice.