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The flu is seemingly everywhere right now, as we return from holiday travel and get back to school and work. If there is one thing that the flu likes, it is people seeing each other inside.
This is true every year, but this year, we’re starting to hear talk of a worse flu season than usual. Media outlets are talking about “Super Flu” or the “Super-K Variant.” But other voices caution that we see the flu every year; is this really any different? On top of this, there is the issue of vaccines. Is the problem that people are avoiding vaccines? Or that the vaccines don’t work? Or both?
Let’s look at what the data really says about the current flu season, if it’s worse and why, and what you can do about it (wash your hands!).
Looking for more on symptoms and treating the flu? Our Flu 101 has you covered.
How bad is the current flu season?
The CDC tracks flu in several ways. The broadest approach is the network ILINet, which includes data from 3,200 medical providers across all 50 states. These providers track and report the share of medical visits for influenza-like illness (fever, cough, in the absence of other diagnosis), relative to overall visits.
This metric reliably tracks the flu season year-to-year and doesn’t rely on the availability of testing, which may vary across space or time.
The graph below shows last year’s flu season, compared to the start of this one. Flu has a clear seasonality; the season is generally worst in January and February. So far, the current season does look worse than last year by this metric. For the most recent week, the share of visits with flu-like symptoms in ILINet is up 22%.
The other way to track the severity of flu this year is with hospitalization rates. Unfortunately, the current season is also looking worse. Hospitalization rates in December 2025 were higher than in December 2024. In the week ending December 28, 2025, the overall hospitalization rate for flu across all ages was 8.4 per 100,000, versus 7.7 in the equivalent week in 2024.
Both metrics point to a flu season that is worse than last year, although perhaps not at the panic levels suggested in some media coverage.
Why is this a worse flu season?
There are basically three reasons a flu season could be worse in one year than another:
- The circulating flu virus could be more severe. The flu has many variations, and some are more contagious or cause more severe illness than others.
- The flu vaccine can be less well-matched to the virus. Flu vaccines are developed each year by making an educated guess in the spring about what variant will be circulating in the fall. This guessing is necessary because it takes time to make vaccines. But if the virus mutates in ways that we do not expect, the vaccine may be poorly matched to the main form of flu that is circulating. This will result in less protection and more flu.
- Flu vaccine rates may be lower. Fewer vaccinated people means more illness.
A fourth possibility is that people interact more and spread the virus more, but outside of the COVID-19 pandemic years, we do not expect much variation in how much contact people have.
In the case of this year, the primary explanation is likely the mismatch with the flu vaccine.
The first possible reason — about the severity of this year’s virus — is hard to evaluate at this point. Both hospitalizations for the elderly and overall flu rates are up about 20% from this time last year. We’ll know more about this as the season goes on.
The third explanation about vaccination rates is also not consistent with the data. About 40% of both adults and children are vaccinated for the flu this year, which is very similar to previous years (it would be better if this were higher!).
How effective is the current flu vaccine?
It is already clear that this year’s vaccine is not well-matched to the virus. The primary circulating strain of the flu is currently H3N2 Subclade K. The “H” and “N” refer to two proteins on the surface of the virus that determine how the virus attaches and releases from cells; they come in different versions, hence the number. Within these HxNx subtypes, there are further mutations which are called “subclades” — smaller variations on the virus structure.
The flu vaccine for this year does cover a form of H3N2, but not the right subclade. As a result, the vaccine effectiveness is lower. How much lower?
We do not yet have much information on this, since the flu season is still in its early stages. So far, there is one paper out of the UK that has estimated vaccine effectiveness based on a fairly small sample. In this paper, the authors look at a sample of individuals who are either admitted to the hospital or visit the emergency room and have a PCR test for influenza. They combine this with data on vaccination and compare the rate of positive flu tests for individuals with and without vaccination. This is one standard way to compute vaccine effectiveness; it provides a sense of efficacy against severe illness.
Based on this approach, the authors argue that vaccine efficacy for children against serious disease is good and similar to previous years, around 70% protection, despite the changes in the circulating virus. For adults, it’s much worse, more like 30% and similar across adult age groups, which is a lot lower than a typical season, where the vaccine might have a 60% efficacy. Based on prior years, these numbers are likely to decline as the season progresses, since the efficacy of the vaccine wanes over time.
What should you do?
I wish I had a magic hack to help you avoid the flu. We cannot live in a bubble away from other people, and the seasonal flu is, unfortunately, a part of life.
Some things you can do.
First, if you haven’t had your kids vaccinated, consider doing so. It’s not too late to protect them from the heart of the flu season, and the early data is most compelling for that group. The CDC has recently changed vaccination recommendations to avoid recommending the flu vaccine to children, but the data shows vaccines can protect against severe disease, and we have already seen pediatric deaths this season.
Second, try to avoid people who are actively sick. I know how hard this is, and it can feel fruitless when kids are already in day care, but trying to stay away from family and friends who are actively ill is beneficial.
Third, wash your hands more. I know, I know, I say this a lot. But there is good evidence, and the mechanism makes sense. If you have the flu virus on your hands and you put them in your mouth, that’s how you get sick. So washing hands is effective.
And finally, if you and your household get sick, consider Tamiflu. Overall, the impacts of this medication for healthy adults are small, but for high-risk individuals (older adults, anyone with immune issues), it can shorten illness and improve outcomes. Perhaps most importantly, there is good evidence on the value of prevention after exposure. If you are high risk — say, because you’re pregnant — and someone in your house gets the flu, this can be taken as prophylaxis.
Overall, flu cases peak in January and February, and then begin to decline in March. By April, the season is mostly over. So hang in there!
The bottom line
- The current flu season is worse than last year, although perhaps not at the panic levels suggested in some media coverage.
- The primary explanation for the worse flu season is that the vaccine is less well-matched to the virus than it has been in previous years.
- For kids, the vaccine still seems to be pretty effective at preventing severe disease. For adults, it’s working less well.
- Getting vaccinated, avoiding sick people when possible, washing your hands, and using antivirals like Tamiflu for treatment or prevention in high-risk cases can reduce severe illness.
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Hi Emily and Parent Data team! It would be helpful to understand vaccine efficacy in the context of the baseline risk of severe disease (or death). So for example, with the vaccine, what are the odds of being hospitalized and/or dying, versus without? (Both for kids and adults). Much of the “panic news” is about kids dying, giving some of us flashbacks to the pandemic (I confess, my knee jerk reaction is to become a hermit)
My family experienced the opposite with children vs adults over Christmas with Flu A. Three of the four children (my two and my niece), 1.5, 5, and 3) were sick with fevers up to 104.4, lasting in total about a week. All children were vaccinated. Of the six adults, three did not mask up, and these three were all vaccinated. Two did not have any symptoms and one experienced a mild cold. The other three adults masked up for a week (aside from meals). Two of these three, who were vaccinated, had no symptoms. One of these three, who was the only one in the house to not have the flu shot, got sick with higher fevers. Fortunately, we were all okay. But the severity was definitely worse with the 3 (vaccinated) youngest kids (the fourth is 9) and the unvaccinated adult.