This Is Not Your Ordinary Flu Season

EVERY FLU SEASON is different. Some come earlier, others later. Some are mild, while others—like last year—barrel through like a tornado. Every year, scientists do their best to predict what type of influenza virus will hit the US based on data from countries in the Southern Hemisphere whose flu seasons come earlier than ours.The key word here is predict. Since the influenza virus mutates quickly, it’s hard for scientists to give a 100 percent guarantee that what’s ravaging Australia will also come for the US. That’s what happened in the brutal flu season last year—and this year.A few weeks ago, scientists gave a forecast of H3N2 (that’s the one dubbed “Super-K”) as the dominant flu strain for the US. But early surveillance in flu cases from the West Coast found that a different type—Influenza A virus subtype H1N1—has overtaken H3N2 as the dominant flu strain in October. The CDC also released new flu data reporting a spike in flu-related hospitalizations.Does H1N1 sound eerily familiar? H1N1 is also known as swine flu—a strain that sparked a pandemic back in 2009. So far, researchers have linked early flu ER visits to a mutation in H1N1 (a G155E mutation) that changes the way the virus attaches to and infects cells. Past research has found antibodies from past H1N1 infections or vaccinations may not recognize it, especially in younger populations. In other words, there is a chance the mutated influenza virus could evade some pre-existing immunity.Here is what you need to know about this early jump to flu season and how to best protect yourself against this mutated strain.What’s the Latest Flu Info?HERE’S WHAT THE CDC learned: In mid-October this year, the agency saw 10 times more hospitalizations for flu than it did in 2025 (2.1 hospitalizations per 100,000 people compared to 0.2 per 100,000 during the same week last year).Among other changes are when and where the virus is spreading. While influenza cases typically tick up around fall, infections began rising in August. The boost of early cases was mostly on the West Coast, including Arizona, Nevada, and California. Hawaii and Louisiana are already at moderate levels. Typically, the US flu season starts in the South.Flu activity remains low nationally. But as of October 28, the CDC estimates that infections are growing or likely growing in 39 states. The numbers coincide with early reports of flu activity ramping up on the East Coast in states including Pennsylvania and New York.Will the Flu Vaccine Still Work Against H1N1 Strain?WHILE SCIENTISTS INITIALLY predicted a “Super-K” flu strain to be dominant, this year’s vaccine accounts for multiple flu strains. The current flu shots will target three strains: H1N1, B/Victoria lineage, and H3N2. It’s too soon to see if the vaccine will fully protect against the mutated H1N1 strain, but it’s still expected to provide some meaningful protection.“A mismatch is not a black-or-white situation. We may have less immunity, not no immunity,” Andrew Pekosz, PhD, virologist at the Johns Hopkins Bloomberg School of Public Health told TODAY.com. You can also take some reassurance from last year when people who still got the mismatched flu shot were still less likely to have severe illness and be hospitalized than those who were unvaccinated.What Are the Options for Flu Vaccines?ALONG WITH YOUR traditional flu shot, adults ages 50 and over are eligible for a new flu vaccine called mFLUSIVA made with the same mRNA technology as the COVID vaccines. A phase 3 clinical trial on the mFLUSIVA vaccine found it was more effective at preventing illness from influenza virus subtypes A and B than a standard vaccine. Reminder, the dominant strain right now is Influenza A virus subtype H1N1.Of the 20,179 people injected with the new shot, only 411 developed a lab-confirmed case (2 percent) 14 days after vaccination during flu season last year. Meanwhile, 557 of 20,124 recipients of the standard vaccine got sick with the flu (2.8 percent).One caveat, however, was that the new flu vaccine has a greater chance of severe side effects. In the clinical trial, people were more likely to report injection site pain, fatigue, headaches, and muscle weakness.Don’t want a shot? That’s fine! You also have your choice of a nasal flu vaccine a.k.a. FluMist if you’re ages 2 to 49. “We tend to develop less of an immune response in the nose as we get older, which means the nasal spray vaccine doesn’t work as well in older groups,” John Sellick, DO, infectious disease expert and professor of medicine at the University at Buffalo, previously told MH.Ultimately, time isn’t running out yet to get yourself armed and ready for the US flu season. The influenza virus is fast and mutates easily, but vaccination remains your best option to weather the storm.Jocelyn Solis-Moreira, MS is the associate health & fitness for Men's Health and has previously written for CNN, Scientific American, Popular Science, and National Geographic before joining the brand. When she's not working, she's doing circus arts or working towards the perfect pull-up.