This flu season is taking off sooner than usual, with more cases than have typically been reported by this point in the year. This trend holds true for Washington state and the country as a whole, but the numbers are worse in Washington than in most other states.

In the first week of December, 3.2% of doctor visits nationwide were from people with an influenza-like illness, according to the most recent data from the Centers for Disease Control and Prevention (CDC). The national baseline — which uses data from the previous three seasons — is 2.4%, and the country has been at or above that number for the past five weeks. At this time last year, the rate was just below 2.4%.

Washington is one of a handful of places in the U.S. with particularly high flu activity, along with Nebraska, Puerto Rico and a swath of Southern states stretching from Texas to Virginia, according to the CDC.

In Washington, 4.4% of doctor visits were from people with a flu-like illness — far above the state’s 1.5% baseline. And 2.78% of King County doctor visits were from flu patients, compared to a baseline of 1.45%.

Also abnormal this flu season: The prevalence of the influenza B virus, a strain that typically shows up later in the season.

While anyone can contract any strain of the flu virus, different strains disproportionately affect different age groups, said Dr. John Dunn, medical director for preventive care at Kaiser Permanente Washington. The B strain of the virus more commonly affects children and young adults, while the A strain is more common among people 65 and older.


The B strain is what is appearing in most cases in King County, where two adults have died since the beginning of the flu season in September. Three adults elsewhere in the state have died of the flu.

The flu virus is a master at mutating to adapt to vaccines, so the World Health Organization (WHO), with input from CDC, consistently creates new versions of the vaccine to stay ahead of it. Each February, health officials and scientists look at which strains are circulating in the Southern Hemisphere to see what might make its way to the Northern Hemisphere; the same evaluation is done of the Northern Hemisphere in September to plan for the Southern Hemisphere. Flu data from public health departments, clinical studies and laboratory results are all taken into account.

How the flu vaccine is made each year to keep up with the virus

But even as its effectiveness varies, health experts say getting the vaccine is always more effective than not getting it. The shot can reduce your risk of catching the flu by 40% to 60%, according to the CDC.

It’s not too late to get a flu shot to protect yourself and those around you, Dunn said. The flu circulates all year, and while the uptick has come earlier than usual, this season probably hasn’t reached its peak yet, Dunn said.

That peak is hard to predict; it hits at a different time each season but generally comes in the first few months of the calendar year, Dunn said.

“You are far more likely to be exposed to the flu in the next two months than you were during the past two months,” he said.

Why your arm hurts so much after getting a flu shot

The flu has already had an impact on at least one group of high-profile locals: the Seattle Seahawks, who are fighting for a spot in the NFL playoffs. Earlier this month, it felled wide receivers Tyler Lockett and David Moore and about eight other members of the team. Defensive end Jadeveon Clowney caught the bug this week.

Moore told Seattle Times reporter Bob Condotta that he declined the flu shots the team offers to players.