Galvanized by the SARS epidemic and the spread of avian flu, the Bush administration issued the first national plan Tuesday for how the country should prepare and respond to a pandemic of influenza, should it strike the United States.

The plan lays out the public health measures that would be crucial in the event of a flu pandemic, including the emergency production of vaccines, the stockpiling of anti-viral drugs, the freeing up of enough hospital beds to care for the sickest, the limiting of public gatherings and the possible imposition of quarantines.

But administration officials said they were unable to resolve the complex practical and ethical issues that could stand in the way of putting these measures into effect. As a result, the plan, which is being published in the Federal Register today, provides only a broad outline of possible actions, which the officials said they hope will provide a starting point for public discussion.

A major concern of the plan is how to stockpile and decide who would get the anti-viral drugs and vaccines that would be in heavy demand but scarce supply. Disease experts believe that an influenza pandemic is inevitable, but when and where it will begin is unpredictable.

Influenza, unlike many other infectious diseases, has the potential to affect everyone in short order in a pandemic.

In the plan, administration officials estimate that from 89,000 to 207,000 Americans, or less than 1 percent of the population, might die, depending on how the influenza virus behaves and spreads. In the 1918-19 influenza pandemic, 500,000 of the more than 20 million deaths worldwide occurred in the United States, where the population at that time was 105 million.

The administration released the plan at this time in part because of the recent experience with severe acute respiratory syndrome, or SARS, and the anthrax attacks.

Also, health officials are deeply concerned about the spread of the A(H5N1) strain of avian influenza that has devastated poultry and bird flocks in Southeast Asia. Experts fear that the genes of A(H5N1) could combine with the genes of a human influenza strain to create an entirely new virus that could ignite a worldwide epidemic.

Tommy Thompson, the secretary of health and human services, said that "a pandemic virus will likely be unaffected by currently available flu vaccines that are modified each year to match the strains of the virus that are known to be in circulation among humans around the world."

Because it takes months to produce a vaccine against a pandemic strain, government officials are working on multiple tracks simultaneously, said Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases.

Tens of millions of standard influenza vaccines are produced on a seasonal basis, and the industry does not have the capacity to produce a pandemic vaccine at the same time. So the government is taking steps to help manufacturers produce vaccine at any time of the year, Fauci said.

But the initial supply will be limited.

Two manufacturers, Aventis and Chiron, are expected to deliver enough vaccine against the A(H5N1) strain to Fauci´s institute in October and November, he said in a recent interview. Safety studies will begin soon thereafter, but the findings are unlikely to come before next spring.

But because the influenza virus mutates quickly and unpredictably, the A(H5N1) strain might change significantly as it causes an epidemic. Or some other strain may cause the next pandemic.

So mass production of the A(H5N1) vaccine would come only if the virus started spreading from human to human, which it has not done so far.

The government has stockpiled enough of the anti-viral drug Tamiflu to prevent or treat influenza in 1 million people. A full course involves taking 10 Tamiflu pills -- two a day for five days. But that would be woefully inadequate to treat enough people in a pandemic.

Officials also said they are seeking help to determine who would get the scarce vaccine and drugs when a pandemic hits.

Doctors want to treat the sickest and those at greatest risk of death. But they must balance this against the need to keep health care workers healthy so that they can care for others, said Julie Gerberding, the director of the national Centers for Disease Control and Prevention. Even if enough Tamiflu could be produced, a question that needs to be answered is "to what extent will taxpayers be willing to invest in stockpiling large supplies of expensive drugs for years in which we don´t use them," she said.

IN WASHINGTON

Public health officials in Washington have been bracing for pandemic influenza or a major act of bioterrorism for two years, but still aren´t ready.

"We´re not there yet," said Dr. Alonzo Plough, director of Public Health -- Seattle & King County. Plough said federal admonitions to improve public health preparedness so far have not been accompanied by enough money.

"We do have a pandemic flu plan for our state," said Tim Church, spokesman for the state Department of Health. But Church said it´s an older plan that is being revised to incorporate the increased threats of bioterrorism and new viruses.

Rather than create a separate plan for each threat, both said, officials are working on a general emergency response plan that could be used in any such event.

More than two years ago, Congress authorized the U.S. Department of Health and Human Services to give states more than $2 billion to beef up public health emergency preparedness. Washington so far has received more than $70 million, of which about $7 million has gone to Seattle & King County.