PUBLIC health experts warn that the world might be close to a repeat of the flu pandemic of 1918, which killed millions. But could it instead be close to a reprise of the 1976 pandemic that never happened?

That is the year President Gerald R. Ford announced a crash program to "inoculate every man, woman and child in the United States" against swine flu. But the virus never became a killer, and vaccinations were halted two months after they began after reports that 500 people who received the shot developed a paralyzing nerve disease and more than 30 of them died.

There are lessons from 1976 that might be applied to today's preparations. A 2004 draft of a government plan for a pandemic listed some.

One is that "making clear what is not known is as important as stating what is known." Another is that a program should be re-evaluated periodically rather than left on autopilot.

And this time, federal officials said, the vaccine won't be used until there are signs a pandemic is under way.

Dr. Fineberg said another lesson is that Congress should provide liability protection for vaccine makers now, rather than waiting until the crisis occurs.

He said the wrong lesson to draw from 1976 would be "the superficially obvious one" - that because it didn't happen then it won't happen now and preparations are not necessary.

Still, repeated cries of wolf can make the public blasé.