As flu season  fast approaches, U.S. health officials are urging all children between the ages of six months and 18 years of age to get flu shots. The recommendation expands the previously targeted population (infants, people 50 and over, those with chronic illnesses and compromised immune systems) to include all school-age kids.

"Flu is very transmissible in school," said Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention (CDC) in issuing the call for some 30 million more U.S. children to get the flu vaccine. "This is truly an effort not only to improve the individual health of children but to affect the population of children as they congregate in schools and day care."

The new advisory, supported by the National Foundation for Infectious Diseases and the American Academy of Pediatrics, is designed to reduce missed school days (and work days for parents) and to cut down on the use of antibiotics to treat influenza. The height of the flu season runs from December to March, but health officials say people should start getting vaccinated  as soon as possible.

Recent reports indicate that there's a surfeit of flu vaccines available this year. "Given the robust supply, the emphasis this year is get out there and get protected," Gerberding said at a news conference.  "And for sure, protect your children."

According to the agency, some 5 percent to 20 percent  of the U.S. population (15 million to 60 million) come down with the flu annually; about 200, 000, including 20,000 children, are hospitalized for symptoms and as many as 36,000 mostly elderly die from flu-related complications. During the 2007-to-2008 flu season, however, the CDC reported that 86 children died from the flu, half of them between the ages of 15 and 17.

A study published last year in the New England Journal of Medicine showed that seniors who received the shot had a 48 percent reduced risk of getting the flu and a 27 percent reduced risk of being hospitalized from the flu or pneumonia.

"The message for most people is get your flu shot," Gerberding said. "It's an advantage to you or someone you care about."

The worst ever flu pandemic in 1918 killed an estimated 20 million to 40 million people worldwide, including  between  500,000 to 675,000 people in the U.S.