Previously the flu had been at a regional level. It was upgraded in a new report, meaning the flu is in more than half of the communities in the state, said spokesman Donn Moyer.
Widespread flu is not unusual, but the activity appears to be increasing and could be worse than the previous two seasons, which were considered mild, Moyer said.
"We get to widespread flu activity in our state almost every season," Moyer said. The activity seems to be a little early. It typically peaks in January and February.
"We're ramping up," Moyer said.
Six people have died of the flu so far this season, including one child, all in Western Washington. There were 18 flu deaths in 2011-2012 and 36 the previous year. The most state deaths were 98 in the swine flu season of 2009-2010.
"Every one of these deaths is tragic, especially one that happens to have been a child," Moyer said. "But the numbers are not unusual."
The department reported the first three deaths in December: a 12-year-old Pierce County boy, and a man in his 80s and a woman in her 70s in King County.
Three more December deaths were reported last week by Snohomish County: a Bothell woman in her 40s, an Everett woman in her 80s and an Edmonds woman in her 80s.
Those are lab-confirmed flu deaths. Officials believe the flu is a complicating factor in more deaths.
The department urges residents to take the risk seriously and head off the aches, stuffy nose and fatigue with a flu shot. There's no shortage of the vaccine in the state, Moyer said. The shots are recommended for everyone over the age of 6 months. The state pays for the vaccine for children, although parents may still be charged a fee for the injection.
The Centers for Disease Control and Prevention (CDC) and local researchers have found that the current flu vaccine is 62 percent effective in preventing the virus this season.
"While the vaccine isn't perfect, the study shows that this year's flu vaccine offers the population substantial benefits in preventing influenza illness and related visits to the doctor," said Michael L. Jackson, an assistant investigator at Group Health.
Health officials recommend that people with the flu stay home for at least 24 hours after the fever is gone to avoid spreading the virus. Rest, liquids and over the counter medicines are common treatments. Antibiotics don't work against a viral illness.