WEDNESDAY, Oct. 7, 2026 (HealthDay News) — Flu season may be getting a head start this year, and experts say that's a good reason not to put off your flu shot.
Flu tests are coming back positive at unusually high rates for early fall on the U.S. West Coast and in the United Kingdom, reports Nature.
In Japan, outbreaks in August and early September forced some schools to close just as students were returning from summer break.
"It would be an incredibly early season" for the United States if West Coast cases keep rising at their current pace, Scott Hensley, a virologist at the University of Pennsylvania in Philadelphia, told Nature. In a typical year, U.S. flu season peaks in December and January.
Most of the early U.S. cases involve a type of flu called H1N1. That's a switch from last season, when a fast-spreading version of another type, H3N2, took over.
H1N1 accounts for 96% of U.S. cases tested for type during the week ending Sept. 26. H3N2 makes up nearly all the rest, and no influenza B turned up, Nature reported, citing federal data.
Still, it's too early to say how the season will play out. The early numbers come from far fewer positive tests than doctors see at the height of flu season.
"An early start doesn't necessarily mean a more severe season," James Hay, an epidemiologist at the University of Oxford in England, told Nature.
Each year's vaccine is designed months before flu season begins, so it doesn't always match the viruses that end up spreading.
This year's shot looks like a good fit for the H3N2 and influenza B viruses now circulating, Hensley said. Whether it matches H1N1 strains isn't clear yet.
Even an imperfect match offers real protection, Hensley added. Last season's vaccine wasn't built for the new H3N2 variant, but it still recognized the virus and gave some protection.
Caitlin Rivers, an epidemiologist at Johns Hopkins University in Baltimore, usually waits until mid- to late October for her own shot. This year, she's thinking about getting it as soon as possible, Nature reported.
"This is one of those seasons where the key message is to go get vaccinated now," Dr. Alex Greninger, a virologist, said.
The U.S. Centers for Disease Control and Prevention (CDC) recommends a flu vaccine every year for everyone 6 months and older, ideally by the end of October.
Vaccination is especially important for those at higher risk of serious complications, the CDC says. That includes young children, pregnant women, adults 65 and older, and people with conditions like asthma, diabetes, heart disease or lung disease.
Babies younger than 6 months are too young for the vaccine, so caregivers should get vaccinated instead.
Along with the flu vaccine, here’s how you can help prevent the spread of germs:
Stay home when sick and avoid close contact with anyone who is sick.
Practice good hygiene (clean hands frequently with soap and water or hand sanitizer; avoid touching your eyes and face; cover coughs and sneezes with a tissue).
Improve air quality (get fresh outdoor air; purify indoor air; have group gatherings outdoors).
Clean surfaces around your home and workplace.
More information
Visit the U.S. Centers for Disease Control and Prevention for more information about preventing seasonal flu.
SOURCES: Nature, Oct. 6, 2026; U.S. Centers for Disease Control and Prevention, Sept. 1, 2026
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