Yes, influenza is actively circulating in the United States. The 2024-2025 flu season has been notably severe, with hospitalization rates reaching their highest levels since the 2010-2011 season. Activity typically peaks between December and February, and this season followed that pattern with widespread high-level activity reported across the country during that window.
How Widespread Is Flu Activity?
During the first full week of January 2026, 36 U.S. jurisdictions (states, territories, and large cities that report independently) were showing high or very high levels of flu-like illness among people visiting outpatient healthcare providers. Of those, 14 reported “very high” activity and 22 reported “high” activity. That level of spread means the flu wasn’t concentrated in one region; it was hitting most of the country simultaneously.
By late February 2026, activity had started to decline in many areas, with some jurisdictions dropping to moderate, low, or minimal levels. That said, flu viruses circulate year-round, and late-season surges in March or even April are not unusual. Over the past 40 years, February has been the most common peak month (18 out of 42 seasons), but six seasons peaked in March and one peaked as late as April.
Which Flu Strains Are Circulating
Influenza A(H3N2) has dominated this season. In late December, over 91% of subtyped influenza A samples were H3N2, with only about 9% being H1N1. Influenza B viruses made up a very small share of cases, roughly 2%, and all of the B viruses that were further tested belonged to the Victoria lineage.
H3N2-dominant seasons tend to be harder on the body. This subtype is historically associated with more severe illness and higher hospitalization rates, particularly among older adults and young children. That pattern held this year.
How Severe Has This Season Been?
The cumulative flu hospitalization rate hit 59.5 per 100,000 people by mid-January, the highest rate recorded at that point in the season since 2010-2011. That number captures lab-confirmed flu hospitalizations reported through a national surveillance network, so the true burden is likely higher since not every hospitalized patient gets tested.
The season was especially hard on children. A total of 280 pediatric flu deaths were reported for the 2024-2025 season, a rate of 3.8 deaths per million children. That’s the highest count since pediatric flu deaths became nationally reportable in 2004, second only to the 2009 H1N1 pandemic season. The median age of children who died was 7 years, and 61% of deaths occurred in children under 9. Infants under 6 months had the highest mortality rate at 11.1 per million, partly because they’re too young to be vaccinated.
How Well Is the Vaccine Working?
Vaccine effectiveness this season has been moderate, which is typical for H3N2-heavy years. For children and teens, the vaccine reduced outpatient flu illness by roughly 32% to 60% depending on the study network, and protection against hospitalization was stronger, ranging from 63% to 78%. Against H3N2 specifically, outpatient effectiveness in children was around 42%, while protection against hospitalization was about 55%.
For adults, the picture was similar. Overall vaccine effectiveness against outpatient flu ranged from 36% to 54%, and protection against hospitalization fell between 41% and 55%. The vaccine performed better against H1N1 than H3N2 in outpatient settings (42% versus 25% for adults), but against hospitalization from H3N2, effectiveness was a more meaningful 51%.
Those numbers may sound modest, but even 40% to 50% effectiveness substantially reduces the chance of ending up in the hospital. If you haven’t been vaccinated yet and flu is still circulating in your area, the vaccine can still offer protection, especially against severe outcomes.
What to Do If You Get Sick
Flu symptoms usually come on fast: fever, cough, sore throat, body aches, headache, and fatigue, often all hitting within a day or two. If you suspect you have the flu, timing matters. Antiviral medications work best when started within 48 hours of your first symptoms. After that window, they can still help people who are hospitalized or at high risk for complications, but the benefit drops.
Rapid flu tests you might get at a clinic or urgent care have a sensitivity of roughly 50% to 70%, meaning they miss a significant number of true infections. The FDA now requires newer rapid tests to meet at least 80% sensitivity. If your rapid test comes back negative but you have classic flu symptoms during a period of high flu activity, your doctor may still treat you based on symptoms alone, or order a more sensitive molecular test.
People at higher risk for complications include children under 5 (especially under 2), adults 65 and older, pregnant women, and anyone with chronic conditions like asthma, diabetes, or heart disease. For these groups, early antiviral treatment is particularly important. Most healthy adults and older children recover within one to two weeks, though fatigue can linger longer.
How to Track Flu Activity in Your Area
The CDC publishes a weekly FluView report that includes a state-by-state map of flu-like illness activity, updated every Friday during flu season. The map color-codes each state from minimal to very high based on the proportion of outpatient visits for respiratory illness with fever plus cough or sore throat. It’s worth noting that this system tracks symptoms, not lab-confirmed flu, so the numbers can also reflect other respiratory viruses causing similar symptoms. Still, during peak flu months, influenza is the primary driver of those visits, making the map a reliable indicator of flu spread in your state.