Illinois Faces Surge in Influenza Deaths as New Subclade K Variant Intensifies Flu-like Illness Activity, Warns IDPH and CDC

In a somber announcement, Illinois authorities have reported the first pediatric death due to influenza this season, as flu activity in the state escalates to a “very high” level.

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The Illinois Department of Public Health is urging residents to remain vigilant and take steps to prevent the spread of the flu, as infection rates continue to rise.

According to the Centers for Disease Control and Prevention, Illinois has reached the highest classification of respiratory illness activity, marked as “Very High.”

Meanwhile, COVID-19 cases in Illinois have also increased, reaching a “moderate” level, as noted by the CDC.

Details regarding the location of the child’s death have not been disclosed, and it remains unclear whether the child had been vaccinated against the flu.

Nationwide, the influenza season has claimed the lives of nine children so far, as reported by the Illinois Department of Public Health.

IDPH said during the 2024-2025 season, Illinois reported 12 pediatric deaths from influenza, six from RSV and three from COVID.

Flu activity is continuing to climb across the U.S. as hospitalizations rise, according to newly released data from the Centers for Disease Control and Prevention.

About 8% of visits to a health care provider were labeled as flu-like illness, surpassing any levels seen since 1997, the earliest for which data is available. Flu-like illness accounts for patients that have a fever as well as a cough and/or sore throat.

Additionally, the CDC says there have been at least 11 million illnesses and 5,000 deaths due to flu so far this season; including at least nine pediatric deaths.

Data shows that the majority of this season’s cases are linked to a new flu strain called subclade K — a variant of the H3N2 virus, which is itself a subtype of influenza A.

Subclade K has been circulating since the summer in other countries and was a main driver of a spike in flu cases in Canada, and the U.K.

ABC News contributed to this report.