Washington ? New research says the best way to protect society’s most vulnerable from the flu: Vaccinate school-age children and their parents.

Kids already top the government’s priority list for swine-flu shots this year because that new influenza strain targets the young. That’s unusual, as flu usually is most dangerous to older adults.

But Thursday’s study, in the journal Science, says vaccinating students should be a priority every year — because schoolchildren are influenza’s prime spreaders and their parents then are the virus’ bridge to the rest of the community. The idea: Inoculating spreaders could create something of a cocoon around the people most at risk of flu-caused death.