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Seasonal, Not Safe: Influenza 2025–2026

  • Writer: Heather McSharry, PhD
    Heather McSharry, PhD
  • 5 days ago
  • 15 min read

Summary

Flu isn’t just seasonal — it’s dangerous.

As the 2025–2026 influenza season intensifies, this episode examines why “just the flu” can be devastating, even for healthy children and adults. From heartbreaking personal stories to the science of viral evolution, we explore what makes influenza so formidable, how policy shifts are weakening our defenses, and what you can do to protect yourself and your community. With expert insights on vaccines, viral spread, antiviral treatments, and future innovations like universal flu vaccines, this post unpacks the reality behind a virus we’ve grown too comfortable with — and why complacency costs lives.

Listen here or scroll down to read full episode.



Full Episode

🛑 Update – CSTE Responds to Vaccine Schedule Changes

After this episode was recorded, On January 6, 2026, at 7:56 pm, the Council of State and Territorial Epidemiologists (CSTE) issued a strong public statement opposing the federal government’s recent changes to the U.S. childhood immunization schedule.

CSTE — the national professional organization representing public health epidemiologists across all U.S. states and territories — warned that the policy shift "threatens the health of all children and families in America." They emphasized that the previous schedule was based on decades of rigorous scientific review and real-world infectious disease surveillance.

In their words, offering vaccine guidance “not based on evidence” is confusing to parents and dangerous to communities. They also highlighted the enormous historical impact of routine childhood vaccines: preventing over a million deaths and saving trillions in societal costs over the past 30 years.



It’s hard to talk about a disease in a way that’s both scientific and deeply human — but that’s exactly what we have to do today. Right now in the United States, influenza isn’t just an abstract number on a CDC dashboard. It’s something that’s touching families in real, heartbreaking ways.

In Ohio, a healthy 16‑year‑old girl went to the doctor with typical cold and flu symptoms. Her parents thought it was a bad bug — nothing unusual — until her fever climbed, her lungs filled with infection, and within days she was gone. They were left trying to understand how something so ordinary could turn so deadly.

And on New Year’s Eve, a 5‑year‑old boy — the son of a well‑known speaker and influencer — died after an 11‑day fight with influenza that turned to sepsis and seizures. His family shared their grief publicly, talking about their faith, the bright spark he was in life, and the unfairness of it all.

These stories aren’t isolated. Influenza is not “just a virus.” It’s both familiar and formidable. Even when it affects healthy kids or young adults, it can escalate fast and without much warning.

Today, we’ll unpack why flu remains a significant threat — from how it spreads and mutates to what’s happening this season, how policies are shifting, and how we can protect ourselves and each other.

This is Seasonal, Not Safe: Influenza 2025–2026.

Where We Are Now

As of early January 2026, the United States is deep in flu season — and this year’s flu season isn’t just bad — it’s breaking records. According to the CDC, outpatient visits for flu-like illness are at the highest level recorded for this point in the season in over two decades, outside of the pandemic. More than 7% of all medical visits are now related to symptoms like fever, cough, and sore throat — a sign that the virus isn’t just circulating, it’s overwhelming care systems.

And while some of that includes RSV and COVID-19, flu is the main driver, especially H3N2. Visits for flu‑like illness are well above baseline, and nearly a third of respiratory samples tested in clinical labs are coming back positive. That’s high, even for mid‑winter.

Influenza A, specifically the H3N2 subtype, is responsible for most of it. Influenza B is circulating at lower levels but may increase later in the season, as it often does.

CDC estimates so far include millions of illnesses, well over 100,000 hospitalizations, and more than 5,000 deaths, including children. Pediatric deaths in particular are sobering, because they are almost always preventable with vaccination and early care.

Globally, the World Health Organization reports that the pattern is similar across much of the Northern Hemisphere — activity increasing in North America, Europe, and parts of Asia. Influenza A dominates nearly everywhere, with H3N2 leading the charge, followed by a smaller proportion of H1N1 and influenza B.

Importantly, there’s no evidence the virus has mutated into something inherently more severe. What’s happening is quantitative, not qualitative — a lot of people infected at once. That means crowded ERs, full wards, and stretched hospitals. Severity on the population level rises not because each case is worse, but because there are simply more of them.

The Policy Earthquake

Before we get into the biology, we need to talk about the policy landscape — because what’s happening in Washington right now has direct consequences for how we protect people from these kinds of seasons.

On January 5th, 2026, the CDC announced one of the most dramatic changes to American immunization policy in decades. The agency rolled back routine childhood vaccine recommendations, including the influenza vaccine, shifting many from universal recommendations to a weaker category called “shared clinical decision‑making.”

And this is confusing for people. Shared clinical decision‑making sounds collaborative, but many families don’t know what it means. In surveys from the Annenberg Public Policy Center, more than a quarter of U.S. adults thought it meant involving family discussions, while others assumed it suggested the vaccine might not be necessary or safe.

In reality, shared decision-making means the vaccine is no longer routinely recommended for everyone — instead, it’s given only if a parent and provider agree it’s appropriate based on personal health factors. But this shift has created confusion at clinics, pharmacies, and schools, especially because most of these vaccines were previously part of the standard childhood immunization schedule.

Critics — including pediatricians and public health organizations — warn that changing these recommendations without new scientific evidence or public health review undermines decades of progress. The American Academy of Pediatrics and many states have stated they will continue following the traditional vaccine schedule, and have reaffirmed their confidence in the safety and necessity of these vaccines.

The problem isn’t the idea of shared decision-making in principle — it’s how it’s being used to quietly downgrade public health standards, at a time when diseases like influenza are surging. And when official guidance gets murky, the result isn’t empowerment — it’s uncertainty. And uncertainty is where preventable illnesses thrive.

This didn’t come from new evidence. There was no major study overturning decades of data showing that vaccines save lives. It followed the 2025 restructuring of the Advisory Committee on Immunization Practices (ACIP) — where experienced vaccine scientists were dismissed and replaced with individuals known for opposing or questioning vaccines.

Under Robert F. Kennedy Jr.’s leadership at the Department of Health and Human Services, ACIP’s integrity as a science‑based body is gone. This matters because ACIP recommendations don’t exist in a vacuum — they shape state policies, school entry requirements, and insurance coverage decisions.

So just as influenza is climbing, the country’s vaccine playbook is being deliberately weakened. When guidance becomes ambiguous, public confidence drops. Schools doubt mandates. Pediatricians get conflicting messages. And parents hear uncertainty instead of clarity.

That’s not an accident — that’s how preventable diseases make comebacks.

It’s worth repeating: viruses don’t care about ideology. Flu doesn’t adjust its infectivity based on political affiliation. And children and vulnerable populations, especially, are the ones who pay the price when prevention turns into a debate instead of a public health standard. But even healthy people are at risk of severe illness and health consequences from the flu.

How Influenza Works

So, let’s unpack the virus itself — what it is, how it works, and why it’s so good at evading us.

Influenza viruses belong to a family called Orthomyxoviridae. That means they are enveloped, RNA‑based, and segmented —meaning their genetic material comes in eight separate pieces. Picture a puzzle with eight moveable parts. If two flu viruses infect the same cell, they can mix and match those segments in a process called reassortment.

That’s part of why influenza is so evolutionarily agile.

There are four main influenza types: A, B, C, and D. Only A and B cause the seasonal epidemics that show up every winter.

Influenza A is the global chameleon, infecting birds, pigs, horses, and humans. It’s divided into subtypes based on two proteins on its surface:

  • Hemagglutinin (HA) — the “H” — which lets the virus attach to cells in your airway.

  • Neuraminidase (NA) — the “N” — which helps new viral particles escape so they can spread.

When you hear H1N1 or H3N2, that shorthand is describing those proteins. H3 means hemagglutinin type 3; N2 means neuraminidase type 2.

Influenza B, by contrast, mainly infects humans and evolves more slowly, but that doesn’t make it harmless. It can be severe, especially in children.

You’ll sometimes hear two other phrases: antigenic drift and antigenic shift.

  • Antigenic drift is the constant, small genetic change — a slow creep that lets the virus escape partial immunity over time.

  • Antigenic shift is rare but profound: a sudden swap of gene segments between different flu strains that can create an entirely new subtype — something our immune systems have little or no memory of. Shifts are what fuel pandemics, like the one in 2009.

This year’s circulating viruses are driven by drift, not shift —so incremental change that gradually reshapes the landscape but doesn’t reset it completely.

Subclade K — The Buzzword of the Season

You might have seen headlines about “Subclade K.” Here’s what that means — and what it doesn’t.

Within H3N2, scientists track small genetic lineages —or branches on a family tree. Each new branch is called a clade, and each offshoot of that branch is a subclade. Subclade K is simply one of those offshoots — and it’s now the dominant H3N2 strain not only in the UK, but also in parts of North America and Japan, based on recent surveillance data. In many regions, it accounts for the vast majority of subtyped H3N2 cases.

It’s not new in the sense of being a different subtype. It’s still H3N2, just with a specific set of seven distinct mutations that differentiate it from the vaccine reference strain. While lab tests showed some immune escape, real-world UK data shows the 2025–26 vaccine remains strongly protective, preventing 70–75% of hospital visits in children and 30–40% in adults. The season also began weeks earlier than usual, suggesting that population-level immunity — lowered by declining vaccine uptake — may be playing a role.

What makes K notable is that it’s been spreading widely this season, meaning it’s well adapted to infect humans. But there’s no sign it causes more severe illness than previous H3N2 versions. The problem isn’t that it’s more virulent — it’s that it’s more successful at finding hosts.

When the number of infections goes up, the number of hospitalizations inevitably follows, even if the average severity stays the same.

So when you hear “Subclade K,” think of it not as “Super Flu,” in fact don't think of any flu as the super flu, that's not a real thing. Flu doesn't have to be some hypervirulent strain to be serious...all the usual flu suspects are dangerous. This situtation with K is, however, a real‑time reminder that influenza is constantly re‑writing itself, one mutation at a time.

“When more children are protected, it helps stop the spread of flu to others around them.” — Dr. Jamie Lopez Bernal, an epidemiologist for UKHealth Security Agency said in a GAVI article.

This season, fewer kids are getting vaccinated against flu. According to the CDC’s National Immunization Survey, flu vaccine coverage among U.S. children is lower than last year — often by 5 to 10 percentage points. Parental intent to vaccinate is also down. And that matters, because this year’s dominant strain, H3N2 Subclade K, is spreading fast — and kids are among the first affected.

Lower coverage means more infections, more ER visits, and more lives at risk — especially for children with asthma, heart conditions, or other underlying health issues.

Transmission: How, Exactly, Flu Spreads

Influenza spreads primarily through respiratory aerosols — small, virus-laden particles released when an infected person breathes, talks, coughs, or sneezes. These range in size from large droplets that fall quickly to the ground, to aerosols smaller than 5 microns that can remain suspended in air for minutes to hours and be inhaled into the lungs.

While influenza is not considered “airborne” in the strict sense like measles or tuberculosis — which can spread over long distances via microscopic particles — it does transmit efficiently at short range through shared air, especially in enclosed, poorly ventilated spaces.

Fomite transmission — infection via contact with contaminated surfaces — is also possible, though it’s thought to be less common than inhalation of respiratory particles. This happens when someone touches a surface carrying infectious virus and then touches their eyes, nose, or mouth, allowing the virus to enter the body.

That’s why hand hygiene remains an important part of flu prevention

The incubation period — the time between exposure and symptoms — averages two days but ranges from one to four. And here’s the sneaky part: you can be contagious before you even feel sick.

Most adults shed virus for about five to seven days; children, infants, and immunocompromised people shed longer. That’s why flu rolls through schools so efficiently — kids cough, play, share air, and viral transmission thrives.

All of this makes indoor air quality incredibly important. Better ventilation, filtration, and simply opening windows when possible lower risk meaningfully. Wearing a well‑fitted mask around vulnerable people during peak season still helps.

Meanwhile, this year hospitals are managing not just flu but also rising RSV and COVID‑19 cases. These overlapping epidemics — sometimes called the “tripledemic” — create diagnostic confusion, share symptoms, and stretch medical capacity thin.

What Happens Inside the Body

Here’s what happens when influenza gets in.

The virus binds to the cells that line your upper respiratory tract, then hijacks their machinery to produce copies of itself. Within hours, those cells die, releasing more virus into the airways and exposing underlying tissue.

Your immune system sees this chaos and responds. Fever, headache, muscle pain, chills, fatigue — those are your immune system’s alarm bells, not the virus itself.

For most people, that reaction clears the infection in about a week. But in some, the immune response becomes overzealous. Inflammation spills into the lungs, the air sacs fill with fluid, and oxygen levels plummet. Bacterial pneumonia can take advantage of the damaged tissue, compounding injury.

This is why complications are so diverse. Influenza doesn’t just live in the lungs — its inflammation ripples through the whole body. It can trigger heart attacks, strokes, neurologic symptoms, and worsen chronic illnesses like asthma or diabetes.

And in older adults, a severe flu episode can tip fragile systems over the edge, leading to declines that last long after the infection clears.

Treatment — Timing Is Everything

Treatment exists, but timing matters.

Antiviral medications — oseltamivir (Tamiflu), zanamivir, peramivir, and baloxavir — can shorten symptoms and reduce complications if started early, ideally within 48 hours of symptom onset. For hospitalized or high‑risk patients, doctors often start treatment even later because the benefit in complications and mortality still holds.

These drugs work differently: oseltamivir and zanamivir block the neuraminidase enzyme; baloxavir stops viral replication earlier in its life cycle. Peramivir is given intravenously for severe cases.

Antivirals aren’t perfect. On average, they reduce symptom duration by about a day in healthy adults, but their real value is preventing escalation — fewer hospitalizations, less pneumonia, fewer deaths.

They can also be used for post‑exposure prophylaxis — given preventively to high‑risk individuals after confirmed exposure, like in nursing homes or households with vulnerable family members.

So far this season, antiviral resistance remains low — a reassuring sign that these drugs continue to work. Surveillance networks across the globe continuously test for resistance, ready to update guidance if that changes.

Still, antivirals are a safety net, not a shield. The most powerful protection remains prevention.

Vaccination — Still the Cornerstone

The influenza vaccine is sometimes maligned for being imperfect, and that’s true in one sense. Effectiveness varies each year, largely due to how well the vaccine strains match what’s circulating. H3N2, our main culprit this season, tends to mutate faster, making matching particularly tricky.

But decades of evidence show a consistent truth: even when the vaccine doesn’t match perfectly, it dramatically reduces the risk of severe illness, hospitalization, and death.

In children, vaccination can cut the risk of influenza‑associated death by more than half. In adults with heart disease, it reduces heart attack risk. And vaccinating pregnant people protects both parent and newborn through shared antibodies.

Two main flu vaccine formulations are available:

  • Inactivated influenza vaccine (IIV) — commonly known as the flu shot. It’s made from killed or split virus particles, primarily containing purified hemagglutinin (HA) protein, which triggers an immune response. This formulation is recommended for most people over 6 months of age, including pregnant individuals, older adults, and those with chronic conditions.

  • Live attenuated influenza vaccine (LAIV) — given as a nasal spray, it uses weakened but live virus that can replicate in the cooler environment of the nose but not in the lungs. It’s approved for healthy individuals aged 2 through 49, but not recommended for pregnant people, immunocompromised individuals, or those with certain underlying conditions and remains an option for those who prefer a needle-free alternative — especially in children who qualify.

For a detailed breakdown of what's in flu vaccines — including how they’re made, what each component does, and special considerations in pregnancy — check out my episode on vaccines in pregnancy, where we go deep on formulation, safety, and immune protection for both parent and baby.

Immunity takes about two weeks to develop after vaccination and tends to wane over several months, which is why annual vaccination remains critical.

This year’s formulation was updated to target the currently dominant H3N2 and H1N1 subclades, as well as circulating B lineages. Preliminary data suggest the vaccine is holding up reasonably well — not a perfect match, but good protection against hospitalization, especially for children and older adults.

It’s never too late in the season to get vaccinated. Flu activity often persists into March or April, sometimes May. If you haven’t gotten the shot yet, getting it now still helps protect you through the peak weeks ahead.

And if you got the flu despite vaccination? That’s not an outlier. Vaccines don’t prevent infection, they prevent severe disease. And this is why we need to stop using sterilizing immunity as the metric for vaccine success. I have an episode explaining this in detail if you’re curious why I say this. Vaccines prep your immune system so it is more effective at fighting the infection and this keeps you out of the ICU, off oxygen, and alive.

Think of it like seatbelts. We don’t judge seatbelts by whether accidents still happen. We judge them by survival. The flu vaccine functions the same way.

But even as the benefits remain clear, uptake is slipping.

Over the past few years, seasonal flu vaccination rates in the United States have declined in both children and adults. According to CDC data from the 2024–2025 season, only 55% of children and 48% of adults received the flu shot — both down several percentage points from pre‑pandemic levels. Among pregnant people, who gain dual protection for themselves and their newborns, coverage fell below 50%.

Some of this drop is due to fatigue — a spillover effect from pandemic-era vaccine debates. Some of it’s policy — with new federal recommendations introducing ambiguity instead of clarity. And some of it is access — as fewer schools, workplaces, and clinics offer flu shots on site.

The result: more people unprotected, more severe cases, and more preventable deaths.

Vaccination remains the single best way to prevent hospitalization and death from influenza — but only if enough people get it.

The Longer View — Building Better Flu Protection

Scientists aren’t just thinking about the next season — they’re thinking bigger.

Around the world, researchers are working on universal influenza vaccines — formulations designed to protect against multiple strains and persist over time, without needing annual updates. Instead of targeting the fast-mutating outer proteins, these vaccines focus on stable internal viral components, like the stem region of hemagglutinin.

Several promising candidates are already in clinical trials. The NIH’s Collaborative Influenza Vaccine Innovation Centers (CIVICs) are supporting a broad portfolio of research, while companies like Moderna are developing mRNA-based flu vaccines that could be updated rapidly and deployed more efficiently. Early results from Phase 1 and 2 trials show strong antibody responses and cross-strain protection.

While universal flu vaccines won’t arrive overnight, the progress is real — and potentially transformative. A world where we don’t need to guess the strain each year, or where one vaccine offers multi-year protection, is within reach.

For now, though, our best defense remains the same: annual vaccination, early treatment, and common‑sense precautions during respiratory season.

Putting It All Together

Influenza is not new. It’s part of our seasonal rhythm. That’s exactly what makes it dangerous — familiarity breeds complacency.

But every year, the pattern repeats: millions infected, hundreds of thousands hospitalized, thousands dead — many of them unvaccinated, many of them young, some of them children whose parents thought it was “just the flu.”

We have the tools. We know what works. Vaccination, early treatment, staying home when sick, clean air, masks when needed, protecting the vulnerable — these are not radical measures. They’re basic acts of care.

Flu doesn’t have to be catastrophic. It becomes so when our defenses — scientific, social, or political — are allowed to erode.

So when you hear someone say, “Oh, it’s just the flu,” I hope you’ll remember what we’ve talked about today. Influenza is seasonal. But it’s not safe.

And the difference between those two words — is everything.


Thanks for being here. Next week we will meet an astronaut from Texas who is running for office and will discuss how science-based policies are non-negotiable for space exploration and national security. Until then, stay healthy, stay informed, and spread knowledge not diseases.










SOURCES

Statement from CSTE on HHS Announcement about Changes to the U.S. Childhood Immunization Schedule https://www.cste.org/news/717529/

Ohio teen dies from flu, marking state’s first pediatric death this season https://www.fox19.com/2026/01/02/ohio-teen-dies-flu-marking-states-first-pediatric-death-this-season/

Catholic influencer Paul Kim’s son, 5, dies after ‘horrific’ case of the flu https://www.kxan.com/news/local/austin/catholic-influencer-paul-kims-son-5-dies-after-horrific-case-of-the-flu/

Annenberg Public Policy Center: CDC Urges ‘Shared Decision-Making’ on Some Childhood Vaccines; Many Unclear About What That Means https://www.annenbergpublicpolicycenter.org/cdc-urges-shared-decision-making-on-some-childhood-vaccines-many-unclear-about-what-that-means/

GAVI Everything you need to know about ‘subclade K’ flu - and vaccine protection against it https://www.gavi.org/vaccineswork/everything-you-need-know-about-subclade-k-flu-and-vaccine-protection-against-it

Fall, A et al, 2023. Evolution of Influenza A(H3N2) Viruses in 2 Consecutive Seasons of Genomic Surveillance, 2021–2023 Open Forum Infectious Diseases

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