Eighteen children dead from flu complications in the U.S.

An early start to the flu season in the United States hospitalized 2,257 people with cases in 41 states and left 18 people dead, according to the latest Centers for Disease Control and Prevention report.

Three-quarters of the people reporting symptoms said they were not vaccinated against influenza, Daily Mail reports.

The CDC said that 29 states and New York City are reporting high levels of flu activity, up from 16 states and New York City the previous week.

"It's about five weeks ahead of the average flu season," Lyn Finelli, the lead of the surveillance and response team that monitors influenza for the CDC, said, according to Daily Mail. "We haven't seen such an early season since 2003 to 2004."

John Brownstein, an epidemiologist at Children's Hospital Boston, is one of the founders of Flu Near You, a project that generates immediate data about the ongoing flu season. He said the most-reported flu symptoms this season are cough at 19 percent, sore throat at 16 percent and fatigue at 15 percent.

Tom Skinner, a spokesman for the CDC, said that the numbers may not have reached their peak.

"I think we're still accelerating," Skinner said, according to Daily Mail.

Flu seasons vary each year in severity with some seasons registering 200,000 hospitalizations and between 3,000 and 49,000 deaths, Daily Mail reports.