The Centers for Disease Control and Prevention (CDC) has officially declared this flu season an epidemic as the complications from it has already claimed lives of fifteen children across the US.

According to the weekly report from CDC, the states that have reported a high rate of “influenza-like” illness activity has rose from 13 to 22 last week. The report further also showed that the outbreaks happened in every region of the country.

This week also reported a climb in the rate of hospitalizations with more and more elderly and children under four showing symptoms of severe complications from flu.

The Tennessee Health Department reported death of at least six children from the flu this year.

According to the CDC, Tennessee is facing the wrath of flu season and is placed under the widespread outbreak category. So far, about 442 children with the flu have been hospitalized in the East Tennessee Children’s Hospital this month.

The health body said that the nearly 90 percent of flu cases reported so far this year have been caused due to the H3N2 subtype. The H3 subtypes are sending the highest number of people to the hospitals and also causing deaths.

According to the experts, there are 17 different kinds of hemagglutinin or H particles and nine different kinds of neuraminidase or N particles. While H particles allow the virus-cell binding, the N particles allow the spread of the infection by the virus throughout the body.

Among the hardest hit regions include the Midwest, south and western parts of the country.