WASHINGTON - The United States may have to close schools, restrict travel and ration scarce medications if a powerful new flu strain spurs a worldwide outbreak, according to federal plans for the next pandemic, obtained Wednesday by The Associated Press. 

It will take months to brew a vaccine that works against the kind of super-flu that causes a pandemic, although government preparations include research to speed that production.

The federal plans have been long-awaited by flu specialists, who say it´s only a matter of time before the next pandemic strikes and the nation is woefully unprepared.

There have been three flu pandemics in the last century, the worst in 1918, when more than half a million Americans and 20 million people worldwide died.

Concern is rising that the next pandemic could be triggered by the recurring bird flu in Asia, if it mutates in a way that lets it spread easily among people.

"We´re all holding our breath," Dr. Julie Gerberding, head of the Centers for Disease Control and Prevention, said in an interview Wednesday.

About 36,000 Americans die from regular flu every winter. Pandemics strike when the easily mutable influenza virus shifts to a strain that people have never experienced before.

It´s impossible to predict the next pandemic´s toll, but a bad one could kill up to 207,000 Americans, says the Pandemic Influenza Response and Preparedness Plan.

Millions of sick patients could swarm doctors´ offices and hospitals, says the plan, which stresses that states and hospitals must figure out now how they would free up hospital beds and perform triage.

There could also be an economic and social wallop from disruption of transportation, commerce, even routine public safety, warns the plan, to be released Thursday by the Health and Human Services Department.

Among its suggested preparations to limit the spread of infection and care for the ill, the plan stresses major federal research to create "seed strains" of worrisome flu types as potential vaccine candidates. Such work might shave a few months off the typical six to eight months it now takes to brew a new flu vaccine, said Dr. Anthony Fauci, the National Institutes of Health´s infectious disease chief.

The plan is a first draft, open for public comment through October. Some big questions remain, including how to ration scarce vaccines and anti-flu drugs during such a crisis. Doctors and public safety workers may be just as important to treat early as frail patients, the HHS plan notes.

"This is a very sensitive issue," said Dr. William Schaffner of Vanderbilt University, who advises the federal government on flu vaccine issues. "Should it be like the Titanic — women and children first — or should it be police and firefighters first? You can see the dilemmas."

Other preparations are under way:

_The CDC is increasing surveillance to better spot dangerous flu strains as soon as they emerge anywhere in the world.

_First on the list of potential pandemic vaccine candidates is the bird flu, which has killed 27 people in Asia this year and prompted destruction of 100 million poultry. Although this H5N1 flu has struck periodically for a few years now, "we´ve never seen so many birds infected with this virus at one point in time," Gerberding said Wednesday.

The NIH is funding production of a few thousand doses of experimental H5N1 vaccine; safety testing is set to begin in November.