Flu season arrives weeks early across the US, with the West Coast hit hardest

Influenza is spreading in the United States weeks ahead of its usual schedule this fall, with the heaviest activity concentrated on the West Coast, according to the latest federal surveillance data released this week. Health officials say it is too early to know whether the early start will translate into a severe season, but they are urging people to get vaccinated now rather than waiting until Thanksgiving or December, when flu shots have traditionally gone into arms.

The Centers for Disease Control and Prevention's weekly influenza report, covering the week ending October 10 and posted October 16, found that seasonal flu activity is "increasing in many parts of the country but remains low" in absolute terms. The agency's clinical laboratories reported that 5 percent of specimens tested came back positive for influenza, up from 3.9 percent the week before. The West Coast, covering the federal health regions that include Washington, Oregon, California, Alaska and Hawaii, is seeing the highest share of cases in the country.

The numbers behind the early rise

A national radio segment examining the trend two days earlier had already flagged the West Coast's unusually early rise, describing a region stretching from Alaska to Hawaii where cases were climbing well ahead of schedule. The CDC's data show a season that, while still mild by historical standards, is moving faster than normal. Emergency room visits coded for influenza rose to 0.8 percent of all visits nationally, and outpatient visits for flu-like illness climbed to 2.1 percent, both increases from the prior week, though still below the national baseline the agency uses to flag elevated activity. Hospitalization surveillance tallied 256 laboratory-confirmed admissions in the reporting week, with adults 65 and older bearing the highest hospitalization rate of any age group. No pediatric flu deaths have yet been reported to the CDC for the 2026-2027 season nationally.

Nearly all of the subtyped influenza A viruses collected so far, 96.4 percent, are the H1N1pdm09 strain, a shift from the H3N2 subclade that dominated and drove unusually severe pediatric illness last season. The CDC's season overview confirms that all three components of this year's vaccines were updated, including a change specifically meant to better match the H3N2 subclade K strain that circulated widely in 2025-2026.

Regionally, the clearest signal has come out of the Pacific Northwest. Seattle Children's Hospital reported roughly 150 pediatric flu cases over a recent two-week span, compared with about 10 cases in the same stretch a year earlier, a jump that one widely syndicated newspaper account described as catching clinicians off guard. In Nevada, the Southern Nevada Health District reported the state's first flu-related death of the season in late September, a Clark County man in his 50s with underlying health conditions.

A season arriving on an unfamiliar calendar

Flu activity in the United States typically builds slowly through the fall and peaks between December and February, giving the vaccine, which takes about two weeks to reach full effectiveness after injection, time to kick in before the worst of the season. This year's pattern has unsettled that timeline. The CDC itself describes the current trajectory as "higher than typically observed at this time of year" while still falling "within expected seasonal variation," a hedge that reflects genuine uncertainty among epidemiologists about what is driving the early curve.

Infectious-disease specialists have floated a possible shift toward H1N1 dominance as one explanation, alongside the usual unpredictability of flu transmission patterns. What is clearer is the muted federal messaging around this year's vaccination push. Unlike in past years, the CDC has not mounted a large-scale public awareness campaign ahead of this flu season, a change from its prior "Wild to Mild" vaccination outreach. Professional medical groups, including the American Academy of Pediatrics and the American Academy of Family Physicians, have issued their own vaccination guidance for 2026-2027 on a schedule that otherwise mirrors the CDC's long-standing recommendation: a seasonal shot for nearly everyone six months and older, ideally administered in September or October, per the agency's interim clinical guidance for this season's vaccines.

Who is most exposed

Adults 65 and older remain the group hospitalized at the highest rate so far this season, consistent with most flu seasons, and the CDC's guidance calls for that group to preferentially receive a high-dose, recombinant or adjuvanted vaccine formulation when it is available. Young children are the other population drawing the most attention this fall, given the surge seen at Seattle Children's and the hospital's description of the timing as unusually early. People with chronic health conditions, including heart and lung disease, also face higher risk of severe illness, officials note, echoing the underlying conditions cited in Nevada's first fatal case of the season.

Dr. Cassius Lockett, the district health officer for the Southern Nevada Health District, framed the Nevada death as a reminder that flu remains a serious annual threat even in a season whose overall severity is still unknown.

"Flu causes serious illness and deaths every year," said Dr. Cassius Lockett, district health officer for the Southern Nevada Health District, who added that older adults, young children and people with certain medical conditions face the greatest risk.

Elsewhere, clinicians have struck a similar note of caution without alarm. Dr. Danielle Zerr, who heads the pediatric infectious diseases division at Seattle Children's, has told reporters the region is running "about two months early" on its usual flu timeline, and has pushed patients to get vaccinated immediately rather than waiting. Caitlin Rivers, an epidemiologist who tracks outbreak-prone pathogens, has advised clinicians to "consider encouraging patients to get vaccinated as soon as possible" given the early activity, rather than holding off until the traditional late-fall window.

What comes next

The CDC's forecast for the season overall still points to moderate severity, with the agency cautioning that it is far too soon in October to have confidence in that projection. Surveillance districts around the country, including Southern Nevada's, are running active flu monitoring through next May, and additional weekly CDC reports will show whether the early West Coast rise spreads to the rest of the country or levels off on its own, as early-season surges have sometimes done in past years without becoming severe nationwide.

For now, the practical guidance from public health officials has not changed, even if the calendar has: get a flu vaccine without waiting for a usual-feeling fall, since protection takes about two weeks to build and this year's shots have been reformulated against updated strains. Nevada health officials have also repeated standard precautions, including frequent hand-washing, staying home while symptomatic, and contacting a health care provider about antiviral treatment rather than toughing out severe symptoms, particularly for older adults, young children and people with chronic illness who make up the bulk of this season's most serious cases so far.