BOISE, Idaho — The Centers for Disease Control says flu season is kicking into high gear across the country, including Idaho.

The CDC says most of the flu cases this year are caused by the H1N1 strain, also known as swine flu.

Experts say the swine flu is seen particularly in people under 40.

So far, 13 children have died from the flu in the U.S. this season.

Doctors say it's not too late to get your flu vaccine if you haven't already.

They say the shot is up to 65 percent effective against this season's strain.

Flu season usually peaks in February.