New research out of California shows that young people and the elderly have been hardest hit by the H1N1 strain of the flu. More people in those age groups have been hospitalized and have died of the flu since it first appeared in the U.S. in the spring.

The California Department of Public Health tracked those who got the H1N1 flu and how sick they became. The study is published in the Journal of the American Medical Association.

"We actually found that over 30 percent of the patients who were admitted and hospitalized required intensive care and mechanical ventilation and over 10 percent died," Dr. Janice K. Louie said.

Tiffany Lee, 16, said she was surprised to be felled by the flu. "I didn't expect to get that sick," she said.

Steve Adams, Tiffany's father, said. “She got really ill really quickly, and the severity of her sickness just started escalating.”

She was hospitalized for more than three months with H1N1. She was on a ventilator and unable to breathe on her own.

 Adams said his daughter was treated for symptoms like a high fever and liver and kidney failure.

At the other end of the age spectrum, the study found that older people, initially thought to have some immunity to the H1N1 virus, were also getting very ill.

“There is a perception that the elderly are protected and have some pre-existing immunity when in fact, in our study, if the elderly were admitted and severely ill, they often ended up dying," Louie said.

The study also reported that infants younger 6 months had a higher risk of hospitalization.

The state of North Carolina reports that 33 people have died of the flu since Sept. 27. Of those, two have been children. A spokeswoman for the state Department of Health and Human Services points out that those deaths could have been from any strain of the flu, although H1N1 is the dominant strain in the population at this time.