In a somber announcement, Illinois officials have reported the first pediatric death linked to influenza this season, amid a surge in flu activity that has reached “very high” levels across the state.

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The Illinois Department of Public Health is urging citizens to exercise caution and take steps to prevent the flu’s spread, as the number of cases continues to rise.

Dr. Robert Citronberg, the executive medical director of infectious disease and prevention at Advocate Health Care, remarked, “We’re witnessing a significant increase in flu cases, more than I have seen in the past several years.”

The Centers for Disease Control and Prevention (CDC) categorize the flu activity in Illinois as “Very High,” which is the most severe stage in their five-tier system for respiratory illness activity.

Meanwhile, COVID-19 cases in Illinois have escalated to a “moderate” level, according to the latest data from the CDC.

Illinois officials did not release where in the state the child died. It was not immediately known if the child was vaccinated.

“It’s really increased sharply in the last few weeks to the point where we’re seeing tons and tons of patients in our clinics and in our emergency departments,” Citronberg said. “We’re seeing severe illness, actually. So we are seeing patients in our intensive care units. And believe it or not, we’ve actually seen some patients die from influenza.”

Across the country, there have been nine pediatric deaths due to influenza this season, IDPH said.

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

In Cook County, the percentage of emergency room visits due to influenza has surpassed the peak of last year.

And the number of flu-related intensive care unit admissions is double what it was last season.

“This is usually the normal pattern of when we get flu, but it is obviously concerning this year just because of the high numbers that we’re getting this time of year,” said Dr. Trevor Lewis, Cook County Health assistant chair of Emergency Medicine. “It probably started the middle part of December. And with the holidays, lots of people gathering with family and friends, and kids going back to school, it’s really spiked these last two weeks.”

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. Illinois one of at least 45 states reporting high or very high flu levels.

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.

Data show 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.

Doctors say it has made this season’s flu shot less effective.

But getting vaccinated is still recommended.

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.

“Even though the flu shot may not be perfect this year in terms of covering the strains, it still helps prevent severe illness and death. So you might still get the flu, but you might not end up in the hospital with it,” Citronberg said.

“It really comes down to hand-washing and hand hygiene when you’re out and about, covering your cough when you’re out in public places with your hand or with your elbow,” Lewis said.

ABC News contributed to this report.