Nearly 400 Washingtonians have died from influenza since October, making the past year the state’s deadliest flu season in over a decade.
Experts still expect several more weeks of flu activity, but the number of U.S. influenza deaths has already surpassed annual totals from each of the last five years, according to the Centers for Disease Control and Prevention.
That’s also true in Washington — where this year’s toll has topped the state’s total from its previous deadliest flu season, in 2017-18. That year, 296 people died from the flu; so far in the 2024-25 season, 388 people have died, including three children, according to the state Department of Health.
The surge of flu illness and deaths has created significant concern in hospitals and among public health teams this season, compared with other respiratory diseases. While COVID was much more mild over the winter, influenza charged through the state in multiple rounds, amid lagging vaccination rates.
Most people who have died from the flu this season have been older adults or had underlying health conditions, the state health department said in its weekly flu report. More than 300 of the 388 deaths have been among those over 65.
Nationwide, the CDC estimates 26,000 to 130,000 people died from the flu between October and early April, according to a preliminary calculation.
The number of deaths in King County is an undercount, “as many flu-related deaths, locally and nationally, are not captured by standard reporting,” Dr. Faisal Khan, director of Public Health – Seattle & King County, said in a Wednesday statement.
The seasonal respiratory virus has had an unusual past five years, taking a back seat for a while when SARS-CoV-2 emerged and dominated in circulation, and also required people to mask, distance and stay inside. During the 2020-21 season, there were no flu deaths in Washington.
Since then, influenza has gradually ramped back up and become more deadly almost every year. Because people’s immune systems were shielded from exposure for so long, they’re now “more susceptible” to the virus, Khan said.
In Washington, flu season has been so forceful that at this point in the year, the state has counted more deaths from influenza than COVID, DOH said this week.
Khan also pointed to specific strains circulating this year that could be contributing to the severity of the season.
According to DOH, the predominant circulating strains this season have been influenza A viruses, specifically H3N2 and H1N1 variants, which historically cause more severe illness and are more infectious than influenza B viruses. The H3N2 strain “tends to mutate frequently, making it harder for immune systems to recognize and respond effectively,” DOH said in a statement.
At the same time, the state is slightly less vaccinated against the flu this year than it has been since at least 2021. So far this season, about 30% of Washingtonians have gotten a flu shot, according to health department data. Last year, about 31.5% were immunized against the flu, and about 33.2% were the year before.
Among Washington children 6 months to 4 years old — typically the most-vaccinated age group after adults over 65 — flu vaccination rates fell 10 percentage points over the past four seasons.
So although last year saw a drop in flu deaths compared to the year prior, this season has so far nearly totaled both combined.
This year, the high death count follows a late-season second wave of infection that drove up flu hospitalization and case rates near the end of January and throughout February. Around that time, about 28% of flu samples from public health labs were returning positive, and patients with the flu accounted for about 7.5% of all emergency visits, according to DOH. Both COVID and RSV emergency visits made up less than 1%.
At the time, UW Medicine emergency physician Dr. Steve Mitchell worried about the high rate of flu hospitalizations — and what it might mean for coming deaths.
“Death is a lagging indicator,” Mitchell, who sees patients at Harborview Medical Center and UW Medical Center Montlake, said in an interview in February.
DOH does not publicly share flu death numbers by county, instead clumping different regions together, and not all Washington county health departments regularly publish their own respiratory virus data.
In King County, 96 people have died from the flu so far this season, according to Public Health – Seattle & King County, which does make data dashboards for COVID, flu and RSV figures publicly available online.
Khan said this has been the deadliest flu season in King County since influenza became a nationally notifiable condition in the U.S. Lab-confirmed flu deaths became a reportable condition to DOH during the 2009 H1N1 pandemic.
In Snohomish County, 39 people have died, according to its health department. Spokane County has counted at least 45 flu deaths, according to its public health department’s respiratory illness data dashboard.
In the CDC’s most recent weekly flu surveillance update, the report called this the “first high severity season” since 2017-18, across all age groups.
Other states are also seeing record-breaking flu seasons. In North Carolina, health officials last week said the state had counted more than 500 flu deaths, the most since tracking began in 2009.
California has tallied more than 1,500 flu deaths since October, according to an early April report from the California Department of Public Heath.
The wave seems to have subsided, for now.
Since March, flu activity throughout the country has quieted, with positive tests declining every week for more than a month, according to the CDC. Flu deaths have also slowed.
In Washington, positive flu tests had plunged to about 6.3% of total samples as of early April, DOH said in its most recent update. The department said it considers flu activity statewide to be low. And in King County, there have been fewer weekly flu deaths reported over the last month, though there are still one to two a week, according to county data.
Vaccination remains the best way to prevent serious illness, especially among older adults, babies and people with underlying health conditions who are at higher risk of flu complications, according to national and state public health experts. The CDC recommends everyone 6 months and older get a flu vaccine every year, with some rare exceptions.
“Staying up-to-date with vaccinations is something each of us can do to help protect infants, the elderly, and those with chronic conditions,” state health officer Dr. Tao Sheng Kwan-Gett said in a written statement.
It’s still “not too late” to get a flu shot, added King County’s public health director. Immunization “could mean the difference between being hospitalized or having mild illness at home,” Khan said.
Correction: A comment by Dr. Faisal Khan, director of Public Health – Seattle & King County, about undercounting the season’s flu death numbers may have implied he was speaking nationally. He was referring to King County.