Influenza does not usually command much attention before Halloween. Many people don’t contemplate a flu shot until a week or two before Thanksgiving. Then they get worried about traveling to family get-togethers. This year is different, though. An early flu season is already showing up in laboratory tests, emergency rooms and hospital admissions. Although influenza activity remains relatively low nationwide, the Centers for Disease Control and Prevention is reporting that flu activity has been climbing since late August or early September.
The strain hitting early and hard is A(H1N1), which is quite different from the influenza A(H3N2/subclade-K) that affected Australia and New Zealand during the 2026 winter in the Southern Hemisphere. Those countries experienced a relatively subdued flu season. Influenza got off to a slow start down under, and overall activity remained substantially lower than in 2025..
Our Early Warning System Failed Us
We frequently look to Australia and New Zealand for an early warning about what we should expect six months later in the Northern Hemisphere. It turns out that we should have been studying South Korea instead. It was the canary in the coal mine. Scientists there were reporting H1N1pdm09 by August and early September. Hospitalizations climbed rapidly.
Guess what is hitting the United States. You got it: H1N1pdm09. And just as in South Korea, hospitalizations are climbing. During the week ending October 17, the CDC’s influenza hospitalization surveillance system recorded an unusually high hospitalization rate for this early in the season, somewhat reminiscent of what was observed in South Korea. No one is panicking, but it is the highest hospitalization rate for this point in the flu season since 2010-2011.
An Early Flu Season Is Showing Up in Several Ways
The hospitalization numbers are not the only warning sign. The percentage of specimens testing positive for influenza has been increasing. So have emergency department visits involving flu and laboratory-confirmed influenza hospitalizations.
During the week ending October 17, hospitals participating in the CDC’s National Healthcare Safety Network reported 4,811 laboratory-confirmed influenza admissions. The hospitalization rate was highest among people 65 and older.
There is also evidence that influenza is getting an unusually early start in certain parts of the country. Louisiana and Hawaii had reached “moderate” levels of influenza-like illness activity while most states were still categorized as low or minimal.
Walgreens has reported another intriguing signal. Based on testing, antiviral prescriptions and sales of cold and flu products, the pharmacy chain estimated that flu activity was running roughly four weeks ahead of recent flu seasons.
That doesn’t mean we are headed for a disastrous winter. It does mean that influenza may not be waiting until December or January to make its presence felt.
New York Flu Cases Jump Sharply
New York provides a dramatic example. More than 3,500 laboratory-confirmed flu cases were reported during the week ending October 17. That was roughly a 400 percent increase compared with the corresponding week last year, according to state health data.
A percentage increase like that can sound scarier than it really is when starting numbers are small. Nevertheless, combined with the national hospitalization data, it reinforces the message that influenza is appearing earlier than usual this fall.
H1N1 Dominates This Early Flu Season
So far, this is overwhelmingly an influenza A season. Of 323 influenza viruses reported by public health laboratories during the week ending October 17, 318 were influenza A and only five were influenza B. Even more striking, among the influenza A viruses that were subtyped, 239 of 241, or 99.2 percent, were influenza A(H1N1)pdm09. None were ordinary seasonal H3N2.
The H1N1 viruses circulating now are descendants of the virus that emerged during the 2009 pandemic. They have been circulating as seasonal influenza viruses ever since.
There is a wrinkle. The CDC reports that recently circulating H1N1 viruses belong predominantly to a group called D.3.1.1 and are continuing to undergo genetic changes. Does that mean this year’s flu vaccine will be a poor match? At this point, nobody knows.
The CDC states:
“It is too early to know what viruses may predominate or to say whether there might be implications on flu vaccine effectiveness this season.”
That uncertainty is worth keeping in mind. Influenza viruses are moving targets, and vaccine effectiveness varies from year to year. This year’s shots may be good…but they are never perfect. We have been tracking effectiveness since 2004. Here is a link to our analysis. Over that time period, the influenza vaccine effectiveness has averaged 40%. Some may think that’s pretty good. I would have hoped for something a lot better.
Is Now the Time to Get a Flu Shot?
For people who plan to get vaccinated against influenza this year, the clock is ticking. The CDC recommends annual influenza vaccination for nearly everyone six months of age and older. For most people, September or October is considered an ideal time.
There is also a practical reason not to wait much longer. It generally takes about two weeks after vaccination for the immune response to develop. A vaccination around Halloween should therefore provide time for an immune response before Thanksgiving travel and family gatherings.
People 65 and older deserve particular attention. They currently have the highest influenza hospitalization rate, and the CDC preferentially recommends one of three vaccines for this age group: a high-dose vaccine, an adjuvanted vaccine or a recombinant vaccine.
Vaccination cannot guarantee that someone won’t catch influenza. The CDC itself acknowledges that vaccinated people can still become infected and transmit flu.
A much bigger question involves whether a flu shot reduces the severity of an infection if someone catches influenza. Some observational studies have found lower rates of intensive-care admission, organ failure or death among vaccinated people who nevertheless develop laboratory-confirmed influenza.
Other studies, however, have found little or no reduction in severity. Because these comparisons are observational rather than randomized, they cannot completely rule out differences between vaccinated and unvaccinated patients that might influence the outcome. Bottom line: Flu shots moderately reduce the likelihood of catching the flu and might reduce the intensity of the infection. No guarantees, though.
“I Thought It Was Just a Regular Cold”
One recent story illustrates why influenza should not always be dismissed as “just the flu.”
ABC7 New York reported this week on 63-year-old Frank Bosco of East Northport, New York. During the previous flu season, what he initially thought was an ordinary cold turned into a catastrophic influenza infection. Bosco spent 116 days in three hospitals. At one point he required dialysis and was placed on a lung-transplant list. He and his wife told ABC that neither had previously gotten flu vaccinations. They are now urging other people to take influenza more seriously.
One person’s experience cannot tell us how well vaccination will work for everyone. But his story is a reminder that influenza can occasionally cause devastating complications even when an illness initially seems routine.
Don’t Forget Antiviral Treatment
Vaccination isn’t the only tool in the toolbox when it comes to fighting off influenza. Prescription antiviral medicines such as oseltamivir (Tamiflu) and baloxavir (Xofluza) can be useful, especially for people at high risk of complications. These drugs generally work best when started as early as possible after symptoms begin.
They are not silver bullets, however. Such drugs have a modest impact on the duration of a flu attack. But we do have a caveat here. Some folks report impressive results while others say the antivirals were worthless or caused unpleasant side effects. We cannot account for the huge variability in responses we have seen from visitors to this website. Here are just a few of our articles:
Protecting Yourself from the Flu with Tamiflu
What Should You Know About Vaccine Effectiveness?
Does Tamiflu Speed Recovery from Influenza? What about Side Effects?
People who develop trouble breathing, chest pain, confusion, severe dehydration or symptoms that improve and then suddenly worsen should seek immediate medical attention.
The Bottom Line on the Early Flu Season
No one can predict in October how severe the 2026-2027 influenza season will ultimately become. The CDC emphasizes that national activity is still relatively low. But this year’s early flu season is providing signals worth paying attention to. Positive tests are rising, emergency room visits are increasing and flu hospitalizations are occurring earlier than usual. H1N1 is currently dominating the viral landscape.
For people who intend to get vaccinated, waiting until influenza is widespread may not make much sense. With Thanksgiving less than a month away, now may be an especially reasonable time to discuss flu vaccination with a health professional.
And if influenza symptoms strike, especially in someone at high risk for complications, please ask promptly whether antiviral treatment would be appropriate. Because you can now purchase home influenza test kits at many pharmacies, why not have a box on hand in case you start to sniffle and sneeze?.
