And while Chicago area medical providers say the number of flu-like cases they've seen in the last few weeks aren't out of the ordinary, they are on the rise.
"Definitely not unexpected. Sometime between the end of December and end of January is usually when flu starts to pick up activity here in Illinois," said Dr. Allison Bartlett, an infectious disease expert at the University of Chicago.
She said her hospital waiting rooms are no exception.
"Part of it is people moving indoors into more crowded conditions," Dr. Bartlett said.
Then throw in the holidays, with plenty of hugging in tight quarters.
"It's nice to get the kids out of school when they're all together with each other sharing germs, but then you bring them to a family gathering where grandma and grandpa are there and may not be as healthy to begin with," Dr. Bartlett said. "It can be a time when we are sharing our germs."
The trend can be seen statewide. In a report published Thursday, the Illinois Department of Health saw an increase of flu-like illness statewide. But the latest levels are below average, and below levels from the same week last year.
The good news is this year's level is still well below last year's. The CDC says in the 2017-2018 season, influenza and pneumonia deaths hit epidemic levels.
But this fall, the federal agency reported vaccination increases. Dr. Bartlett said concern about last year likely contributed to more people getting vaccinated this time around.
"The type of flu that's around right now is the kind that is a very good match with the vaccine. So extra reason to go out and get it," she said.