Current Flu Activity in Illinois: March 2026 Update

Current Flu Activity in Illinois

Illinois is seeing flu activity this March as the 2025-2026 season continues to wind down. As one of the most populated Midwest states, Illinois flu data is closely tracked by the CDC’s ILINet surveillance network.

Check the Illinois flu activity page for the exact ILI rate this week, trend charts, and nearby state comparisons.

How Illinois Compares to Nearby States

The Midwest tends to see flu peaks slightly after coastal states. Here’s how Illinois’s neighbors are doing:

Indiana flu activity — Eastern neighbor
Wisconsin flu activity — Northern border
Iowa flu activity — Western neighbor (18 impressions in GSC)
Missouri flu activity — Southern border
Michigan flu activity — Great Lakes neighbor
Kentucky flu activity — Southeast neighbor

What Else Is Going Around in Illinois?

Flu isn’t the only thing circulating. Illinois residents can check:

Illinois RSV activity — RSV hospital admissions
Illinois COVID-19 activity — ER visit trends
Illinois measles cases — 2026 case tracking
Illinois MMR vaccination rate — Kindergarten coverage
What’s going around in Illinois? — Full health dashboard

When Will Flu Season End in Illinois?

Nationally, the 2025-2026 flu season peaked in January-February and has been declining since. Illinois typically follows the national pattern. Most years, significant flu activity tapers off by late April in the Midwest, though sporadic cases continue year-round.

If you haven’t gotten a flu shot yet and flu is still circulating in your area, the CDC says it’s not too late. Flu vaccination is recommended as long as flu viruses are active.

About This Data

Illinois flu data comes from the CDC’s ILINet network — a system of outpatient healthcare providers who report the percentage of patient visits for influenza-like illness (fever plus cough or sore throat) each week. See our methods page for details.

Updated weekly. See the Illinois flu dashboard for current data.