(WZZM) - The number of flu cases continues to rise across the United States. According to the Centers for Disease Control and Prevention more than a third ofthe states are on the verge of epidemic levels.

Across the country more than 2,200 people have been hospitalized. 18 children have died so far this flu season. Three of them in Michigan.

Experts say some groups are more at risk for flu complications than others.

You can test your knowledge of the flu on the CDC website with a Flu IQ widget.