Influenza has swept into the Pacific Northwest weeks ahead of schedule, catching pediatric hospitals off guard.

The Seattle Times reports that Dr. Mary Fairchok of Mary Bridge Children's Hospital in Tacoma was surprised when a young boy was admitted with flu nearly a month ago, and flu-related emergency visits have spiked since late September at levels doctors say are more typical of December or January.

Seattle Children's saw about 6% of its emergency patients sick with flu in early October, up from 0% a year earlier, according to pediatric infectious disease physician Dr. Erin Chung.

Colorado is also seeing the flu as its most active respiratory virus, with 58 hospitalizations through last week, compared with 39 from COVID and four from RSV, The Colorado Sun reports.

The scale of the early wave is what makes this season surprising.

According to The Seattle Times, King County's flu emergency department visits in the last week of September were higher than at that time in any year since at least 2018, and in the first week of October hospitals saw more than 400 flu patients, versus the fewer than 50 typically seen this time of year.

Nine county residents have died from flu complications since late September. Providence Swedish reports a 330% increase in positive flu tests compared with this time last year, a jump even sharper among adults 50 and over.

Chung called it "an unprecedented early season," prompting a scramble to get patient vaccines available sooner.

The data pointing to an early, active season comes from multiple hospital systems and state trackers.

The Seattle Times reports that about 20% of Seattle Children's influenza A tests were positive in early October, up from under 2% in August, per UW Medicine data, and that the state Department of Health had not updated its weekly influenza report in a month as of Friday.

Meanwhile, The Colorado Sun reports Colorado logged a record 5,900-plus flu hospitalizations last season, including more than 1,100 children and eight pediatric deaths, and 207 flu deaths across 2025.

Early signs this year point to H1N1 as the dominant strain rather than last season's shape-shifting H3N2, which should bode well for vaccine effectiveness, Dr. Suchitra Rao told The Colorado Sun.

Doctors say it is too soon to know whether the early start means a worse or merely longer season.

The Seattle Times quotes Dr. John Pauk of Providence Swedish saying the trend "isn't reassuring" and raises concern about a more prolonged flu season, while Dr. Andrew Young warns the real danger would be if the surge tilts toward older adults.

Rao told The Colorado Sun that the Southern Hemisphere had a less-severe season than the prior two years, but added, "I stopped making predictions about the flu a long time ago."

Staying home when sick, hand-washing, masking in crowded indoor spaces, and improving ventilation remain the mainstays of prevention.