U.S. Prepares for Possible Flu Outbreak WASHINGTON - Closing schools, restricting travel and rationing scarce medications may be the nation's first protections if a powerful new flu strain spurs a worldwide outbreak because it will take months to brew a vaccine, say government preparations for the next pandemic.    Specialists say it's only a matter of time before the next one strikes, and concern is rising that the recurring bird flu in Asia could be the trigger if it mutates in a way that lets it spread easily among people...