What To Know About This Year's Flu Season In Lake County

This flu season in Lake County has been milder than last year, with fewer hospitalizations, no ICU deaths so far, and a shorter stretch of high activity — even as the potentially severe H3N2 strain has made its way to the U.S.

Tanya Glade, Marketing and Communications Specialist with the Lake County Health Department, answers five of our key questions about what residents need to know, including trends in cases, circulating strains, and why vaccination is still recommended.

From hospitalizations to tips for staying protected, Glade provides a clear snapshot of flu activity and what residents should keep in mind as the season continues.

Can you provide an update on what you are seeing regarding respiratory illnesses and flu at this point in the season? Does it seem like the worst is behind us and cases are leveling off?

Respiratory illness activity, including flu, appears to have peaked during the week of December 21. Since that time, we’ve seen consistent week-over-week declines in flu and overall respiratory activity.

Emergency Department visits and other syndromic surveillance indicators for upper respiratory illnesses are continuing to trend downward. Based on historical patterns, when activity reaches these lower levels, we typically do not see a significant resurgence later in the season.

That said, respiratory virus season is not over. We will continue to closely monitor trends in flu and other circulating viruses in the weeks ahead and adjust our guidance as needed. To follow respiratory activity weekly in Lake County, check out our weekly surveillance reports: https://www.lakecountyil.gov/826/Communicable-Disease-CD-Program#weekly-reports

How does this year’s flu season compare to previous years in terms of cases, hospitalizations, and severity?

• Overall, flu activity in Lake County this season has been lower and less severe compared to last flu season.

• Through week 7 of the 2025–2026 season, 2.4% of all Emergency Department visits were due to flu, compared to 3.4% during the same time period last season. We have also seen fewer ICU hospitalizations — 50 this season compared to 96 at this point last year.

• In terms of severity, there have been no deaths among flu-related ICU patients so far this season, compared to an 11% mortality rate among flu ICU patients at the same point last year.

• Additionally, while we have experienced periods of very high flu activity this season, it has been shorter in duration — three weeks above our high-activity threshold compared to eight weeks last season.

We will continue monitoring flu trends closely, but at this time, indicators suggest a milder season compared to 2024–2025.

Are there any specific strains of the flu circulating in Lake County this season that the public should be aware of?

• At this time, the strains circulating in Lake County are consistent with what is being seen nationally during the 2025–2026 flu season. According to the Centers for Disease Control and Prevention (CDC), influenza A viruses are predominant this season.

• One strain of note is influenza A (H3N2), specifically the H3N2 Subclade K variant. This strain was first identified in the Southern Hemisphere and has since spread throughout the Northern Hemisphere, including the United States.

• Historically, H3N2 strains are known to be associated with more severe illness, particularly among older adults and individuals with underlying health conditions

How effective have the flu vaccines been in Lake County this season, and would you encourage residents to get vaccinated if they haven’t already?

We do not have Lake County–specific data on seasonal flu vaccine effectiveness. Vaccine effectiveness is typically assessed through national and international surveillance systems rather than at the county level.

According to the Centers for Disease Control and Prevention (CDC), interim estimates from the Southern Hemisphere—where flu season precedes ours—provide early insight into how the vaccine may perform in the Northern Hemisphere (https://www.cdc.gov/mmwr/volumes/74/wr/mm7436a3.htm). Early estimates from England for the 2025–2026 flu season show vaccine effectiveness against flu-related hospitalization within expected ranges: approximately 70–75% among children and 30–40% among adults (https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2025.30.46.2500854). These findings suggest that flu vaccination continues to be an important tool in preventing serious illness and hospitalization.

In the United States, CDC-supported flu vaccine effectiveness networks are currently collecting real-world data for this season. Early estimates are typically released once sufficient data are available. Looking at last respiratory virus season (2024–2025), immunization reduced the risk of flu-related hospitalization by up to 78% in children, underscoring the vaccine’s role in preventing severe outcomes.

We strongly encourage residents who have not yet received a flu vaccine to do so. Vaccination remains the most effective way to reduce the risk of serious complications, including hospitalization and death—particularly for young children, older adults, pregnant individuals, and people with chronic medical conditions.

Even if someone has already had flu this season, vaccination can still provide protection against other circulating strains and may lessen the severity of illness in the event of reinfection. Getting vaccinated not only helps protect the individual but also helps safeguard vulnerable members of our community who may be at higher risk of severe disease.