SEATTLE — A second powerful wave of influenza has washed over many parts of the country this winter, including Washington, where flu patients are filling hospital ERs and deaths have already surpassed last season's total.

Nationally, more people died of flu than COVID during one week in late January — the first time that's happened since the coronavirus pandemic began, said state epidemiologist Dr. Scott Lindquist.

That's not yet necessarily the case in Washington, though some public health researchers say this year influenza could be pushing out other viruses, like COVID and RSV, given its mysterious rebound at a time when flu season is typically starting to ramp down.

The late-in-the-season rise in cases also comes as the state's flu vaccination rate has dipped.

Flu activity remains elevated nationwide, according to the Centers for Disease Control and Prevention. In addition, this season is now classified as "high severity" for all age groups — the first since the 2017-2018 year, when more than 80,000 people in the U.S. died.

In Washington, there was a peak in flu cases and emergency visits in late December, before they fell in early January.

"Then, boom, it spiked again," said Dr. Steve Mitchell of the Washington Medical Coordination Center, a system based at Harborview Medical Center that facilitates transfers between hospitals throughout the state. "And we're still spiking up."

As of mid-February, about 28% of flu samples from public health laboratories were testing positive, according to the state Department of Health.

Emergency department rates for flu fell about 0.5% from earlier this month, but still account for about 7.5% of all hospital emergency visits. Both COVID and RSV make up less than 1%, per DOH.

"It's been a bad season," Mitchell said. "We think the rate of (flu hospitalization) rise is slowing a little. We're hoping it's kind of plateauing now."

Over the past two weeks, flu hospitalizations statewide have hovered around 515 to 520 patients, Mitchell said.

His staff at the center are very busy this time of year, as they try to balance patients at health care facilities throughout the state to manage bed space and staff capacity. The majority of requests come from smaller, more rural hospitals that need to send patients to larger health care facilities, he said.

At the Providence Swedish emergency department in Mill Creek, this month has been its busiest February in 12 years.

"It's still getting busier and busier," said Dr. Loren Gorosh, medical director of the stand-alone emergency department. "Usually, we get some relief by now. A lot of it probably has to do with seasonal flu cases."

Flu activity here has fluctuated in recent years, as it's fought for attention among other emerging respiratory viruses.

Largely isolating and wearing masks kept flu spread low in 2020 and 2021. But in 2022, after the omicron variant had started to wane and mask mandates were relaxed, the state's death count for influenza jumped tenfold.

That season, 272 Washingtonians died from the virus, compared with 26 in 2021 and zero in 2020, according to DOH. This year, we've seen 177 deaths. About 285 people, meanwhile, have died from COVID.

Snohomish County last week reported its deadliest flu season in three years, with 15 deaths compared with 10 and 12 in previous years.

Six people died from the flu in King County last week, bringing the season's total to 38, according to the county's public health data. More than 30 were older than 65 years old.

Still, the state's flu deaths are far from the total reached during the 2022-23 season, one of Washington's deadliest flu seasons in the past decade. During the worst season, between 2017 and 2018, about 296 people died here.

But Mitchell worries that flu hospitalizations remaining high could be a foreboding sign for the season's overall death toll.

"Death is a lagging indicator," said Mitchell, who also sees patients as medical director of Harborview's emergency department. "I'm hoping we don't catch up to two years ago."

That's why it's still important to get vaccinated for influenza, he and other public health and medical experts said.

"One of the most effective measures is vaccination," Snohomish County's health officer Dr. James Lewis said in a statement this month. "A flu shot remains crucial in reducing the risk of severe illness this season."

Gorosh, at Providence Swedish Mill Creek, agreed that it's not too late to get vaccinated for the flu or COVID. In Washington state, about 2.3 million flu doses have been administered this season, meaning about 29% of the population has been vaccinated against influenza.

It's the lowest flu vaccination rate at this point in the season in past four years. From 2021 to 2024, more than 30% of Washingtonians had received a flu shot by late February, according to DOH.

"I thought after the COVID pandemic, we'd have more respect for some of these respiratory viruses in general," Gorosh said. "That just doesn't seem to be the case overall, and that's kind of been a disappointment for me coming out of the pandemic."

The CDC recommends everyone 6 months and older get a flu vaccine every year, especially people at higher risk of experiencing severe illness. Wearing masks, washing hands frequently and staying home when sick all also remain good prevention strategies, Mitchell said.

These daily practices can go a long way in supporting health care facilities and avoiding serious illness when hospital bed space is so strained, he said.

"Every year is a little different," Mitchell said. "But things are very tight right now."

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