WASHINGTON - The Bush administration, battered by criticism over its hurricane response, is getting the nation prepared for a possible travel ban and other restrictions in the event of a worldwide flu outbreak. Improving vaccines is expected to take center stage as President Bush announces his strategy Tuesday to battle the next flu pandemic, whether it is caused by the worrisome Asian bird flu or some other super-strain of influenza. Preparations are expected to cost at least $6.5 billion. States and cities are awaiting their first specific instructions on such things as who should get limited doses of vaccines and the antiviral medications Tamiflu or Relenza. Topping that list are workers involved in manufacturing flu vaccine, health workers caring for the ill, and other first responders such as police and ambulance drivers, said a public health specialist shown a recent version of the plan. The principal goal of Bush's plan, Health and Human Services Secretary Michael Leavitt said Tuesday, "is the capacity for every American to have a vaccine in the case of a pandemic, no matter what the virus is." "There is no reason to believe that in the next day or two or week or month that that's going to occur," Leavitt said on CBS's "The Early Show." But he added that "we do need to be ready in case it begins to mutate into a human transmissable disease." In his speech Tuesday at the National Institutes of Health, Bush will first note that it will take more than the federal government to battle a super-flu, said White House spokesman Trent Duffy. "America has this tough-it-out strategy when you get sick," Duffy said. "You aren't helping yourself or the country going to work when you get ill. You are potentially threatening a greater health issue if you send children to school when they are sick." Pandemics strike when the easy-to-mutate influenza virus shifts to a strain that people have never experienced before, something that has happened three times in the last century. While it is impossible to say when the next super-flu will strike, concern is growing that the bird flu strain known as H5N1 could trigger one if it mutates to start spreading easily among people. Since 2003, at least 62 people in Southeast Asia have died from H5N1; most regularly handled poultry. The nation's strategy starts with attempting to spot an outbreak abroad early and working to contain it before it reaches the United States. International cooperation "represents a best hope of stopping the lightning spread of a pandemic," Duffy said. There is a possibility that a pandemic would force restrictions of international travel and commerce, he said — one reason the plan will stress improved vaccine manufacturing here. Today, most of the world's vaccine against regular winter flu, including much of that used by Americans each flu season, is manufactured in factories in Britain and Europe. The government already has ordered $162.5 million worth of vaccine to be made and stockpiled against the Asian bird flu, more than half to be made in a U.S. factory. But the administration plan, to be released in more detail on Wednesday, calls for more than stockpiling shots. It will stress a new method of manufacturing flu vaccines — growing the virus to make them in easy-to-handle cell cultures instead of today's cumbersome process that uses millions of chicken eggs — as well as incentives for new U.S.-based vaccine factories to open. Such steps will take several years to implement, but the hope is that eventually they could allow production of enough vaccine to go around within six months of a pandemic's start. "The notion is that prevention beats therapy," said Dr. William Schaffner of Vanderbilt University, an influenza specialist who advises the government on vaccination and has received some information about the plan. Hoping to spur the long-awaited pandemic plan, the Senate last week passed $8 billion in emergency funding for Bush to spend on the preparations.