With winter nearly here and holiday celebrations ramping up, health officials are encouraging flu vaccinations and raising concerns about a new flu variant.

The A H3N2 type of influenza virus, notorious over the years for leading to hospitalizations and deaths among older people, is showing up most so far this flu season. The Oregon Health Authority reports that 58.2% of positive tests analyzed at the Oregon State Public Health Laboratory have been H3, compared with 41.2% that were H1N1.

The good news is that H3N2 is one of three variants included in the 2025-26 flu vaccine. The concerning news is that a mutation of that strain, one called subclade K, has become most prevalent this year.

Subclade K accounts for 89% of the H3N2 viruses that the U.S. Centers for Disease Control and Prevention has collected and analyzed since late September.

The World Health Organization reported last week that subclade K has been detected in at least 34 countries in the past six months.

Even though it is not yet clear how effective this year’s flu vaccine will prove against subclade K, health experts are emphasizing that flu shots remain vital because they can reduce severity of illness, protect against other strains and help reduce overall spread.

“It’s not too late to get your flu shot, especially before the upcoming holidays,” Dr. Howard Chiou of the OHA’s public health division said in a statement. “The flu shot is the best way to help make sure you don’t miss out on holiday festivities or get other people sick.”

The CDC recommends flu vaccines every year for anyone 6 months or older. Nearly 1 million Oregonians had been vaccinated as of early this month, according to the Oregon Health Authority. But that number is about 5% lower than at the same time last year, which OHA said continues a trend of declining flu vaccine rates in recent years.

People can search for a place to get vaccinated by entering their ZIP code at the VaccineFinder website.

Flu cases have remained low in the United States so far, with high rates in only four states: Colorado, Louisiana, New Jersey and New York. But cases are on the rise before an expected peak in the early spring.

OHA has recorded 63 hospitalizations associated with influenza in Multnomah, Clackamas and Washington counties since flu season began Oct. 1.