LOS ANGELES (The New York Times News Service) -- If one child gets the flu this year, a classroom of children is at risk. Parents stay home from work. Emergency rooms become flooded.

That's the scenario federal health officials want to avoid this flu season. So the U.S. Centers for Disease Control and Prevention released new recommendations this year targeting children from 6 months to 18 years, especially those attending school.

"Schools are reservoirs for influenza," said Curtis Allen, a CDC spokesman. "This age group of children visit the doctor and emergency rooms more than those between 20 to 45 years old. And if a child is sick for a week or so, that means that their parents have to stay out of work. When they do become ill, they are taking the flu home to their relatives, and some of their relatives may have health complications."

The pendulum swing from the focus on the old to the young came after the CDC and other health experts said younger children are the first to get the flu, causing a ripple effect.

While the flu vaccine still is recommended for those 50 and older, caregivers and those with compromised immune systems, health experts say children are the key to help fight the spread of flu.

"The evidence is quite clear that that's a group where flu spreads very rapidly and has a major impact within the community," said Dr. Jonathan Fielding, director of the Los Angeles County Department of Public Health, adding that everyone should get the flu vaccine, barring extreme circumstances like egg allergies.

But some parents might disagree, citing questions about a possible link between general childhood vaccines and autism suggested in the last few years.

"I think there's a lot of concerns among parents (about) vaccines in general because parents are feeling overwhelmed," said Dr. Karen Lewis, a pediatrician at Kaiser Permanente Panorama City Medical Center who specializes in infection control.

And misconceptions that the vaccine actually causes the flu persist, Lewis said.

"Children are by far the most likely to become ill because they spread it very readily. They are contagious longer than adults," she said. "There's a huge ripple effect to parents, grandparents, caregivers."

Another misconception is when the vaccines should be given. Flu season begins in October and peaks in January.

"There's a myth that you should wait because some people say the vaccine can wear off," said Dr. Chris Tolcher, a pediatrician at Providence Tarzana Medical Center.

He said it's not too early to get a flu shot.

But, he noted: "It's hard to convince parents of healthy kids to get the flu shot."

About 5 percent to 20 percent of the population gets the flu in any given year. More than 200,000 people are hospitalized from flu complications and about 36,000 people die from flu, doctors say.

Nationwide last year, 86 children younger than 18 died.

Officials with the CDC said this year's vaccine should be a closer match to this year's dominant flu strain than last year's, when only 40 percent were fully protected from the flu, which is lower than usual. In most years, 80 percent of those vaccinated are often protected.

But there still is no guarantee that vaccinating children can prevent widespread flu because each season differs, experts said.

And flu seasons of the past few years have been mild to average.

Copyright 2008 The New York Times News Service. All rights reserved.