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Flu season 2026 is starting early across the United States, and the West Coast has the most activity so far. Here is what the latest CDC numbers show and why experts say to get a flu shot now.
Key Takeaways
- Flu activity has been rising since late August or early September, the CDC says. Overall, it remains low.
- About 3.6% of flu tests were positive in early October, compared with 0.6% a year earlier, Axios reported.
- In the CDC’s newest report, for the week ending October 10, clinical lab positivity reached 5.0%.
- The West Coast has the highest activity. Region 9, which includes Arizona, California, Hawaii and Nevada, hit 9.5% positivity in an earlier report.
- CDC says everyone should ideally get a flu shot by the end of October.
Why Flu Season 2026 Is Starting Early
Flu usually builds in the fall and peaks between December and February. This year, however, it showed up sooner.
According to Axios, about 3.6% of flu tests came back positive in early October. At the same point last year, the rate was just 0.6%. That is a sixfold jump, Scientific American noted.
Importantly, the change is not a quirk of counting. Axios said CDC’s published methods for calculating test positivity have not changed.
One Strain Is Driving the Rise
Most positive tests so far are H1N1, a subtype of influenza A. In the CDC’s newest report, 96.4% of subtyped flu A samples from public health labs were H1N1.
Andrew Pekosz is an immunologist at Johns Hopkins. He said the circulating H1N1 “seems to be a little bit different” from the vaccine strain. He called it an antigenic drift. As a result, the virus may spread more easily, he told Scientific American.
What the Latest CDC Flu Data Shows
So how big is the jump in flu season 2026? The CDC published its FluView report for the week ending October 10 on October 16. It says flu activity is increasing in many parts of the country but remains low.
Here are the main numbers from that report:
- Clinical labs found flu in 5.0% of samples, up from 3.9% the week before.
- About 2.1% of outpatient visits were for flu-like illness, still below the national baseline of 2.9%.
- Hospitals reported 4,024 lab-confirmed flu admissions for the week.
- CDC has received no reports of flu-related child deaths so far in flu season 2026.
CDC also said early activity is higher than usual for this time of year. Even so, it remains “within expected seasonal variation.” The agency noted that all data are preliminary and may change.
The West Coast Has the Most Flu
The highest activity is on the West Coast, in federal health Regions 9 and 10, CDC said. Earlier data put Region 9 at 9.5% positivity, according to Scientific American. Experts called that exceptionally high for this time of year.
“It’s not unheard of to see things rising at this stage,” Pekosz said. “But it’s also something that we probably shouldn’t be seeing until maybe November or December at the earliest.”
Does an Early Flu Season 2026 Mean a Worse Winter?
Not necessarily. Experts say it is too early to predict how severe flu season 2026 will become.
Trish Perl, an infectious disease specialist at UT Southwestern, calls flu season “reliably unreliable.” She told Axios the early rise is worth watching. Still, it does not yet show how bad the season will become.
Who Faces the Most Risk
The strain matters because it affects who gets sickest. For example, H3N2 seasons have historically hit older adults hard. H1N1, by contrast, has had a greater effect on younger people. Both can cause serious disease at any age, though.
Right now, the highest rates of flu-like illness visits are in children, Axios reported. Meanwhile, CDC data show adults 65 and older have the highest flu hospitalization rate.
When to Get Your Flu Shot This Season
Experts agree on one point for flu season 2026: get your shot soon. “‘Get your flu shot now’ is my best advice,” Perl told Axios.
CDC says September and October are good times for most people to get a flu shot. Ideally, everyone should get a flu shot by the end of October, according to CDC guidance for older adults. Also, it can take up to two weeks for the shot to build full protection.
Pekosz said immunity is strongest for about four to six months. So, a September or October shot should cover the worst of the season. “The best time to get vaccinated is before you see influenza in your area,” he added.
Shots for People 50 and Older
On August 5, 2026, the FDA approved Moderna’s mFLUSIVA for adults 50 and older. It is the first mRNA seasonal flu vaccine. In a phase 3 trial, it was 26.6% more effective at preventing flu than a standard shot.
However, access appears limited so far, Scientific American reported. Meanwhile, CDC prefers higher-dose or adjuvanted flu shots for people 65 and older. If those are not available, a standard shot is still recommended.
What to Do If You Get Sick
Prescription antiviral drugs can treat flu, CDC says. They work best when started early. Perl noted that drugs such as Tamiflu may also shorten the time you are contagious.
In addition, CDC urges simple daily habits. These include washing hands often, covering coughs and avoiding people who are sick. For more on preventable illness, see our report on US measles cases and who needs an MMR shot.
Frequently Asked Questions
Is flu season 2026 starting early?
Yes. CDC says flu activity has been increasing since late August or early September. Positivity is higher than usual for this time of year.
Where is flu activity highest right now?
The West Coast has the highest activity, CDC says. Region 9 includes Arizona, California, Hawaii and Nevada.
When should I get a flu shot?
CDC says most people should ideally get a flu shot by the end of October. However, getting a shot later still helps while flu is spreading.
Does an early start mean a severe season?
Not necessarily. Experts say it is too early to know how severe this winter will be.
Who can get the new mRNA flu vaccine?
The FDA approved Moderna’s mFLUSIVA for adults 50 and older in August 2026. So far, access appears limited.
Sources
- Weekly US Influenza Surveillance Report: Key Updates for Week 40, ending October 10, 2026 (CDC FluView)
- Flu and People 65 Years and Older (CDC)
- Flu is showing up earlier this year (Axios)
- This year’s flu season is starting early. Does that mean it will be more severe? (Scientific American)
