U.S. lawmakers have heard more details about the need for a comprehensive global strategy to combat a possible pandemic. Scientists fear the current strain of avian influenza has the potential to kill millions of people.  

"The ramifications would be so significant, so world changing, that we have no alternative but to prepare."

So said Michael Leavitt, the Secretary of Health and Human Services, to a U.S. Senate hearing. He said a pandemic would kill as many as two million Americans and hospitalize more than 10 million others.

"The good news is we have a vaccine,? said the secretary.  ?The scientists at NIH have developed a vaccine with sufficient immune response that it can protect a human being when given in proper dosage. The bad news is we fundamentally lack the capacity to manufacture it in sufficient volumes in time."

Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, says the U.S. needs to sharply increase the number of people who receive annual flu shots.  Dr. Fauci says, that way, vaccine makers trying to meet demand will have sufficient stocks of specific vaccines when the need arises.

U.S. President George Bush has asked Congress to set aside $7.1 billion to prepare for that scenario. The president wants to overhaul the vaccine industry, stockpile anti-flu drugs and work with the international community to contain any potential outbreaks.

"A flu pandemic would have global consequences, so no nation can afford to ignore this threat, and every nation has responsibilities to detect and stop its spread," said the president in a speech earlier this week.

According to the U.S. government plan, travel restrictions or other measures could be imposed to stop a potential outbreak.

Secretary Leavitt said, "There may some who say they cried ?wolf,? but I would like to say that this is about long-term pandemic readiness."

Despite the massive U.S. commitment, officials are warning people not to panic, but some experts say the economic impact of a pandemic scare is already being felt. China has banned imports of poultry from 14 countries and tourism has declined in some South East Asian countries.

John Barry, the author of "The Great Influenza" says the disruptions will likely continue because the world has not taken the threat of influenza seriously until now.

"We don't know when the next pandemic is going to come,? said Mr. Barry.  ?If it comes next year we're in serious trouble, if it waits ten years, chances are pretty good we'll be able to handle it, certainly better than we could today."

No one knows when the next pandemic will come but scientists say the warning signs are already here.  The most likely candidate is the bird flu virus known as H5N1, which has spread from Asia to Europe since it was first detected in 1997. 

Sixty-two people have died and more than 120 people have been infected after coming into contact with the diseased birds.