Community Health & Wellness

Flu cases rise as public health experts study new strain

Flu activity in the Puget Sound region rose quickly over the last month and public health experts worry it could be the start of a particularly bad flu season.

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Right now, 3.3% of emergency room visits statewide stem from influenza, according to the latest data from the Washington state health department published on Dec. 27. That high level of activity surpasses the threshold that requires masking in health care settings. 

A screenshot of the state Department of Health’s respiratory illness dashboard for flu.

“Over the past several weeks, we have had a significant increase in activity of influenza,” Dr. Herbie Duber, Kitsap Public Health District’s interim health officer, said during a board meeting Tuesday. “[That’s] not a complete surprise after holiday gatherings. It’s flu season. We tend to see a spike around now.”

Masks and vaccinations

Dr. Christopher Baliga, medical director of infection prevention and control for Virginia Mason Franciscan Health, also reported an increase in respiratory infections like the flu and RSV in recent weeks. VMFH, owners of St. Michael Medical Center in Silverdale and St. Anthony Hospital in Gig Harbor, will require staff to wear masks when interacting with patients starting Wednesday, he said. The hospitals also encourage patients and visitors to mask-up.

“We also continue to offer vaccinations,” Baliga said. “Vaccines remain one of the best ways to protect ourselves and those we care about this season.”

The West Coast Health Alliance recommends flu shots for everyone six months and older, including those who are pregnant, planning to get pregnant, postpartum or lactating. Washington provides free vaccines, including flu shots, to children 18 and younger. 

Influenza activity has yet to reach the same level as last year, a particularly severe flu season that saw ER use rates peak at over just over 8% in February and a seasonal death toll of 507. Emergency room use for the flu right now remains about 2 percentage points lower compared to this time last year. There have been 22 lab-confirmed deaths.

“While we are currently well below where we peaked for flu activity in 2025, we expect flu activity to continue to rise in the coming weeks,” Kenny Via, a spokesperson for the Tacoma-Pierce County Public Health Department, wrote in an email. “Influenza activity can follow different patterns in different geographic areas; however, we are concerned that the circulating strain of seasonal influenza could make this a more severe flu season.”

Subclade K

The latest data from the Centers for Disease Control and Prevention show elevated rates of the flu across the country. Increases likely will continue into the new year.

“It is very difficult to predict a flu season,” Andrew Pekosz, a professor of molecular microbiology and immunology at John Hopkins University Bloomberg School of Public Health, said at a press conference last month. “But right now we’re at the beginning of what will probably be a pretty severe influenza season, driven primarily by the Subclade K Virus.”

The Subclade K strain is a mutation of Type A Influenza that has been referred to as the “super flu.” It was identified in 2025 and led to an earlier start to flu season and higher than normal case rates in the United Kingdom and other countries outside the United States, Pekosz said. 

Researchers are still working to understand if this strain is more likely to cause severe illness or if it is only better at evading immunity and making individuals more susceptible to infection, Pekosz said. Flu shots continue to remain the most effective protection from serious illness, even though Subclade K may be able to evade some of the vaccine’s protections.