What You Need to Know About This Year’s Flu Season
There are several interesting, frustrating, and concerning trends with influenza this year that parents need to know about.
Earlier Start and Dramatic Ramp-Up
First and foremost, the flu season is ramping up dramatically in early January. It started earlier than in previous years, tracking with what we saw in the southern hemisphere earlier in 2025 where the flu season arrived earlier and ramped up much more precipitously than in years past.
This is because the predominant strain, H3N2, has a new subclade strain (specifically subclade K) causing more symptoms and has evolved enough to evade much of the immune protection from previous flu infections.
Vaccine Effectiveness
The UK, which is a little ahead of us symptom-wise, is seeing that the flu vaccine is effective but not as effective as in years past at protecting against the more severe, long-lasting, and hospitalization-requiring versions of influenza. We are still recommending vaccination knowing that it’s imperfect, but if it keeps you out of the hospital, reduces fever by a day or two, or prevents you from spreading it to loved ones as severely, it’s worth getting.
Early UK data shows 70-75% effectiveness against hospitalization in children and 30-40% in adults. Last season’s vaccine showed 32-60% effectiveness for outpatient visits and 63-78% for hospitalizations in children.
Unusual Vomiting and Diarrhea
One unusual finding with influenza this year is the amount of vomiting and diarrhea accompanying the flu. This is confusing because when people usually say they have “the flu,” they mean vomiting or diarrhea—the “stomach flu”—which isn’t influenza at all.
But this year, influenza, the respiratory illness that causes high fever, body aches, joint pain, difficulty breathing, and dehydration, is also often starting with at least a day or two of vomiting and sometimes diarrhea as well.
This has been noted not just in our practice and community, but around the country. This H3N2 variant is causing significantly more gastrointestinal symptoms and higher, more prolonged fevers.
High and Prolonged Fevers
We’re seeing fevers of 102-104°F lasting for days, rather than the typical brief day or two of fever followed by general malaise. This is an important pattern to watch for.
Pediatric Deaths
There have already been a handful of pediatric deaths this season. Last year’s flu season (2024-2025) saw 280 pediatric deaths—the highest number since the swine flu epidemic in 2009.
Last year had the highest number of pediatric flu deaths on record, and this year is shaping up to be worse in terms of overall flu illness burden in communities.
In fact, the cumulative hospitalization rate this season is the third highest since 2010-11, with at least 560,000 hospitalizations and 38,000 deaths reported.
When to Come In
If your child gets the flu and is at high risk for more severe complications—children under age two, those with asthma, respiratory issues, or neurological conditions—it’s important to come in for a swab and testing. If positive for flu, we’re more likely to treat with Tamiflu or Zofluza.
Outside of these high-risk categories, our approach varies depending on your child’s specific context and family situation. In some cases, we’ll swab and treat, especially if there’s a young sibling at home or high-risk relatives in close contact.
Supportive Care
For most cases, treatment for the flu is supportive care. When uncomfortable, use ibuprofen for children over six months or Tylenol for under six months to control temperature.
It’s important to understand that when we have a fever and are uncomfortable, our body works harder, burning more metabolic energy, making it more difficult for the immune system to fight the flu.
If your child is uncomfortable, it’s worth treating with pain medication. If your child is home from school with a 103°F fever but playing happily on the trampoline, let them be. If they’re miserable on the couch at 103°F, breathing fast and hard because their metabolic rate has increased, give them ibuprofen.
Hydration Tips
Ensure your child stays hydrated. Whatever fluids your child typically drinks are best. If you’re having difficulty keeping them hydrated, diluted apple juice is an excellent option.
Half apple juice, half water has been shown to prevent dehydration, works as well as Pedialyte, and tastes better. Most families already have apple juice on hand, making it more convenient than running to the store.
Watch Respiratory Effort
Monitor your child’s respiratory effort and work of breathing carefully. Children can have significant difficulty with the flu, including labored breathing, rapid breathing, and prolonged respiratory distress. This is a key focus when managing influenza symptoms.
Warning Signs of Complications
There have been multiple pediatric deaths already this year. Last year saw more cases than typical of brain inflammation associated with flu.
While feeling run down and tired is typical for the flu, if your child is acting abnormally or you can’t wake them up as usual, seek medical attention. Obviously, seek immediate care for seizures, but if anything seems significantly wrong, it’s worth consulting your doctor.
This information isn’t meant to scare you, but to emphasize that flu is serious and we take it seriously.
Our typical approach is often ibuprofen, fluids, and checking in the next day. But as a broad public health measure, preventing influenza is crucial.
Impact on the Elderly
While children and adults who get the flu are very likely to survive, the situation is more complex for the elderly.
Even when elderly patients survive the flu, they face a higher risk of death in the following six months. The toll on the body and ongoing inflammation increases their risk for heart attacks and strokes for six months after recovering from the flu.
Influenza causes the familiar temporary symptoms—runny nose, cough, congestion, fever. But for elderly patients, especially grandparents, it significantly increases their risk of stroke, heart attack, and death for six months following infection.
Why This Strain Is Different
The H3N2 subclade K variant emerged in August 2025, after vaccine composition for this season was selected in February 2025. This timing means only 8.6% of circulating H3N2 viruses are well-recognized by the current vaccine, though partial protection still reduces severe disease.
H3N2 tends to evolve faster than other influenza strains, with large antigenic jumps typically occurring every 3-4 years. The subclade K variant has seven new mutations that allow it to evade existing immunity, which is why it’s spreading so effectively.
One encouraging development: In September 2024, the FDA approved FluMist for self- or caregiver administration for people ages 2-49, which could improve access for families who have difficulty getting to clinics for vaccination.
I hope this information has been helpful. Please drop your questions in the comments below—I’d love to answer them and help you navigate your child’s health and wellness this flu season.
