By Derrick Blakley

(CBS) — Got the sniffles? Feeling achy? Could be the flu.

Cases are on the increase, and they’re showing up earlier this year. In fact, in Illinois, the Department of Public Health says confirmed cases are widespread across the state.

CBS 2’s Derrick Blakley reports a certain age group is being hit hard.

The dramatic increase in flu cases statewide this year has taken infection disease experts by surprise. Now, some hospitals, including Advocate Christ Medical Center, are taking new steps to protect their patients.

Walk into the hospital, and you’re met with a stop sign. Starting Monday, visitors under age 18 are restricted from visiting patients—another effect of the rapidly spreading flu.

“Illinois is one of the highest-infected states in the United States. It has had a major effect there, since about the second week of November,” Dr. Stephen Sokalski.

Along with Christ, at least two other Chicago area hospitals have instituted the same restrictions: Advocate Condell in Libertyville and Northwest Community in Arlington Heights. The reason is partially because it’s kids under 18 who are being most affected by this season’s flu wave.

The outbreak’s so severe, emergency rooms like the one at Christ Medical Center have been inundated. Between Dec. 7 and 12, Christ had 132 flu cases confirmed by testing.

Sokalski, head of the infectious disease unit, says that means many more in the community are sick but haven’t sought treatment.

“It’s still increasing dramatically,” he says of the current volume of cases.