President Bush summoned vaccine manufacturers to a White House meeting Friday, hoping to personally boost the rickety industry amid increasing fears of a worldwide outbreak of bird flu. It's the latest in a flurry of preparations for a possible pandemic after criticism of the government's response to Hurricane Katrina.

This month, vaccine maker Sanofi-Pasteur begins the first mass production of a new vaccine that promises to protect against bird flu, producing $100 million worth of inoculations for a government stockpile.

But it would take months to create a new vaccine from scratch if a different strain of bird flu than today's known as H5N1 emerges. Even if the vaccine works, Sanofi is producing enough to protect anywhere from 2 million to 20 million people — depending on how much must be put into each dose — and it's not clear when or where similar large stockpiles could be made.

The nation has only three main manufacturers of vaccine against the regular flu that circulates each winter.

Bush called together the heads of major vaccine companies "to press ahead to expand our manufacturing capacity for a vaccine to address this risk," White House spokesman Scott McClellan said Thursday.

On the agenda for Friday's meeting is liability, McClellan said. If healthy people suffer side effects from a vaccine, manufacturers can face huge lawsuits, one reason many companies have left the business in the last two decades.

Another reason is that vaccines simply aren't very profitable, especially flu vaccine, which must be made fresh every winter to keep up with newly circulating strains. The irony: Although there have been three shortages since 2000 and supplies are strained again this year, in most years manufacturers throw away millions of unused flu shots.

"We cannot handle the threats we face today with a broken flu vaccine system," said Sen. Hillary Rodham Clinton, D-N.Y.., who with Sen. Pat Roberts (news, bio, voting record), R-Kan., introduced legislation Thursday that would, among other things, financially guarantee a market in return for more vaccine production.

A spokeswoman for one manufacturer who plans to attend Friday's White House meeting said a pandemic will transcend those issues.

"When you're actually in a pandemic situation, it's all hands to the wheel," said Nancy Pekarek, spokeswoman for GlaxoSmithKline, which hopes to begin testing its experimental bird flu vaccine in people next year. "It's got to be many, many people producing what they can."

Later this month, the Bush administration will issue updated plans to deal with a pandemic, and a key part will be "how to revitalize that industry in a way to have the capacity not just that it meets H5N1 but any potential pandemic virus," Health and Human Services Secretary Mike Leavitt told The Associated Press.

Scientists have been warning for two years that bird flu in Southeast Asia is growing more ominous and the nation must prepare.

"If the avian flu were to hit here, it would be like having a Category 5 viral hurricane hit every single state simultaneously. We're not ready for that," said Shelley Hearne, director of the nonprofit Trust for America's Health, which backed the vaccine legislation.

"The lawmakers in the last few months have been paying attention," said Hearne, who cites Hurricane Katrina as a key reason.

The Bush administration has been criticized for not getting help fast enough to devastated Gulf Coast states after the storm.

Bush has pushed the focus now on bird flu, by suggesting Tuesday that the military might be needed to enforce mass quarantines and by repeatedly raising the specter of a pandemic.

In the flurry of activity, the Senate last week passed legislation authorizing $4 billion for additional purchases of anti-flu medication. The vast majority is to buy Tamiflu, a pill to both treat and possibly prevent bird flu but that is in short supply. Leavitt has called for a Tamiflu stockpile to treat 20 million people, but the government has enough for just 4.3 million so far.

Influenza pandemics erupt every few decades — the worst was the 1918 Spanish flu that killed some 50 million people worldwide — when the virus mutates into a uniquely different strain. The world is overdue; the last pandemic was in 1968.

Even the ordinary flu kills 36,000 Americans every year. The bird flu so far has killed only about 60 people, mostly poultry workers, even as it has killed or led to the slaughter of millions of birds. But if it changes so it can spread easily from person to person, it would be catastrophic because people have no natural immunity to it.