OLYMPIA — Flu season has been slow to arrive in Washington state, but influenza is now increasing in most of the state’s communities.

It can be difficult to predict the timing and severity of each flu season, and this season has proven to be no exception, arriving later than usual. While flu most commonly peaks in February, Washington state has not yet reached its peak flu activity this season.

“Flu is a serious disease that puts many people in the hospital and claims a lot of lives each year in our country,” said Washington State Secretary of Health Mary Selecky. “Fortunately, we have a vaccine that offers the best protection against flu. We can all do our part to protect our communities.”

Everyone 6 months and older should get a flu shot each year. Some children under the age of 9 may need two doses, administered about four weeks apart, to be fully protected.

The flu is different from a cold. It often causes fever, cough, sore throat, muscle aches, headaches and fatigue. Most healthy adults can spread the flu before they know they’re sick and for up to seven days after. Children can spread it for even longer. To avoid spreading the flu, people should wash their hands, cover their cough and stay home if they’re sick.

If you’re sick with flu, antiviral medications can lessen your symptoms and help prevent serious complications. They work best when started quickly. People at high risk for complications who develop flu-like symptoms should contact their doctor promptly to see if they need medication. Those at high risk include people with certain medical conditions, pregnant women and women who have recently given birth, as well as young children and adults 65 years and older.

Flu season is gaining momentum at a time when whooping cough is already very active in many communities in the state. Anyone can get whooping cough, but it is most serious for infants. All teens and adults should get a whooping cough booster, called Tdap vaccine, to help stop the spread of this disease and to protect babies.

To find an immunization clinic, call your health care provider, visit a local pharmacy, use the Washington State Department of Health Flu News website or call the Family Health Hotline at 1-800-322-2588. The Flu Vaccine Finder is also a good resource.

The state Department of Health website at www.doh.wa.gov offers a healthy dose of information. You can also find the Department of Health on Facebook, and follow it on Twitter.