In the week ending January 10, 2026, influenza was listed on 3.2 percent of the death certificates for deaths in Chicago, the highest weekly flu share in the eight seasons of the Chicago Department of Public Health’s file, and for the second winter in a row flu’s peak topped COVID-19’s: 3.2 percent against 1.4, after 2.6 against 2.2 the winter before. COVID-19 was once listed on 45.2 percent of a week’s deaths, in May 2020; RSV has never passed 0.8 percent. Averaged over the 49 weeks on file for 2025–26, flu and COVID-19 ran even, each at 0.21 percent of a week’s deaths.
Chicago Department of Public Health, Provisional Deaths Due to Respiratory Illnesses (6ibj-qcjr), weekly through September 19, 2026, file updated October 2, 2026 · deaths that occur in Chicago, a virus listed anywhere on the certificate · shares only, no counts · the season figures are oursHow often is flu on a Chicago death certificate?
Seldom above 1 percent of a week’s deaths, except at the winter peak. Flu reached 1 percent or more in 8 weeks of 2024–25 and 3 of 2025–26, and not in a single week of 2020–21 or 2021–22, the two seasons when COVID-19 was listed on as much as 30.6 and 31.7 percent of a week’s deaths. Flu’s peak share was 2.1 percent in 2022–23, 2.0 in 2023–24, 2.6 in 2024–25 and 3.2 in 2025–26; in 2018–19 and 2019–20 it peaked at 1.6 and 1.7.
| Season | Flu, highest week | COVID-19, highest week | RSV, highest week | Weeks flu above COVID-19 |
|---|---|---|---|---|
| 2018–19 | 1.6% (February 16, 2019) | 0.0% | 0.3% | 19 |
| 2019–20 | 1.7% (March 21, 2020) | 45.2% (May 9, 2020) | 0.7% | 11 |
| 2020–21 | 0.4% (September 4, 2021) | 30.6% (December 5, 2020) | 0.4% | 0 |
| 2021–22 | 0.6% (July 2, 2022) | 31.7% (January 22, 2022) | 0.5% | 0 |
| 2022–23 | 2.1% (December 3, 2022) | 5.0% (December 17, 2022) | 0.5% | 1 |
| 2023–24 | 2.0% (January 6, 2024) | 4.3% (January 13, 2024) | 0.5% | 2 |
| 2024–25 | 2.6% (January 18, 2025) | 2.2% (October 5, 2024) | 0.8% | 15 |
| 2025–26 | 3.2% (January 10, 2026) | 1.4% (February 14, 2026) | 0.7% | 9 |
When does the flu peak come?
In December or January, in each of the last four seasons: December 3, 2022, January 6, 2024, January 18, 2025 and January 10, 2026. The two earliest seasons on file peaked later: 2018–19 in the week ending February 16, 2019 and 2019–20 in the week ending March 21, 2020. Our reading: in the last four seasons flu’s share of Chicago deaths peaked between the first week of December and the third week of January. The same 2025–26 winter, flu reached 8.5 percent of emergency-room visits at its peak, the most in nine seasons of the department’s emergency-room record, as our emergency-room page found.
Is COVID-19 still the larger share?
Not at the winter peak, and only about even across the year. COVID-19 averaged 1.62 percent of a week’s deaths in 2022–23 against flu’s 0.15; in 2024–25 flu’s average, 0.43 percent, passed COVID-19’s, 0.37, for the first time in the file, and over the 49 weeks on file for 2025–26 the two were even at 0.21. COVID-19’s highest weeks in those two seasons came outside the flu peak, in the weeks ending October 5, 2024 and February 14, 2026. Our reading: on these certificates COVID-19’s surges have shrunk below flu’s winter peak and no longer arrive with it, while flu’s share still comes in a few weeks.
What can’t this file tell you?
How many people died: the file gives each virus’s share of a week’s deaths and no counts. It covers deaths that occur in Chicago, so a suburban resident who dies in a Chicago hospital is in it and a Chicagoan who dies elsewhere is not. A virus listed on a certificate may be the cause or one condition among several. The weeks are provisional and are not revised as later certificates arrive, and the weeks ending November 22, 2025 and August 22, 2026 are missing. The department’s own description says the file shows trends and is not official death statistics. It carries no age or vaccination detail.
Where does the record live?
The weekly shares are in the city’s Provisional Deaths Due to Respiratory Illnesses file. The same department’s flu-shot records, by age and ZIP code, are on our vaccination page, and its emergency-room counts on our emergency-room page.
- Source the Chicago Department of Public Health’s Provisional Deaths Due to Respiratory Illnesses (6ibj-qcjr), read October 9, 2026: 414 weeks from the week ending October 6, 2018 through September 19, 2026.
- Measure the file’s weekly percent: deaths with the virus listed as an immediate cause, contributing factor or other significant condition, over deaths from all causes, for deaths that occur in Chicago.
- Seasons the file’s own season label, early October to late September. A season’s average is the plain average of its weekly shares; its highest week is the week with the largest share.
Computed by KCM Desk from the health department’s weekly file, read October 9, 2026. Nothing here is medical advice. Human-guided and edited — about this desk. If you spot an error, corrections come first.
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