By Suzanne Le Mignot

CHICAGO (CBS) — The flu season in Chicago is starting with a twist.

As CBS 2’s Suzanne Le Mignot reported Monday, a certain type of influenza virus that we usually see near the end of the season is making a surprise early appearance.

“We are definitely seeing upwards of 20 or 30 patients a day testing positive for flu,” said Dr. Allison Bartlett, a pediatric infectious disease specialist at the University of Chicago Medical Center. “We’re seeing a lot more influenza type B than we often do this time of year.”

Bartlett said flu B is often seen in the spring. She said while flu B is a little less severe and has the same symptoms like fever and body ache, it can lead to a hospital stay and even death.

“Getting vaccinated is the best defense that we have,” Bartlett said, speaking to Le Mignot via Skype. “It’s not perfect, but it helps prevent infections or keep the symptoms more minor – so it’s really important that everyone get vaccinated. It’s not too late this year.”

Bartlett said it’s not known why type B is more prevalent right now.

“I think it’s probably got a foothold in the area, and if the vaccine isn’t quite as good as a match, that allows it to be the one that’s spreading more readily,” she said.

The Cook County Department of Public Health said in suburban Cook County right now, emergency room visits for the flu are up and have been increasing for seven weeks.

From August through the present date, there have been 25 people hospitalized, in intensive care, because of the flu.

So besides the flu shot, what is the best defense when it comes to not getting the flu or passing it on to others, when you have it?

“Making sure that we’re doing a good job of covering your mouth when you cough and washing your hands, and staying home when you’re sick,” Bartlett said. “We have a lot of problems with people who feel obliged to drive themselves to work when they’re not feeling well, putting their colleagues at risk.”

The Illinois Department of Public Health recommends hospitals not allow visitors under the age of 18, because children are known to be high risk when it comes to transmitting viral infections.