If a flu pandemic breaks out in the United States, as many as 4 in 10 school-age children will become sick, according to the U.S. Department of Health and Human Services, which released a comprehensive plan on how it would deal with such an outbreak. The nearly 400-page plan says the department would consider measures such as closing schools early in a pandemic to combat flu pandemic and to help control its spread, especially before a vaccine was available or while it was in short supply. School closings would accompany other measures, such as restricting travel, screening people from affected areas, and isolating infected persons. Though school health experts caution against overreaction, they agree that preparedness is paramount. They say that districts need to begin work now to ensure they are not caught sleeping. The federal plan, issued amid worries about avian flu, places children low on the list of groups that would have priority for receiving vaccines, because they generally have been at a low risk for hospitalization and death in prior pandemics and during the annual flu season. Anecdotal reports suggest the spread of a pandemic can be better controlled when schools are closed early in an outbreak. School districts are advised to come up with their own plans on how to respond to an influenza pandemic.