The preparedness plan released yesterday for a possible flu pandemic grapples with a question for which there is no definitive answer: how to plan for a public health disaster that could kill tens of thousands of Americans as early as this winter but that may not arise until 10 years from now -- and may never occur in the form currently anticipated?

Those and other uncertainties were at the core of the challenge that officials faced as they crafted, with increasing urgency in recent months, a response to avian flu -- a disease that today poses a serious risk only to birds but, with a few mutations, could become a human plague.

In preparing that 396-page plan, officials had to balance a number of competing concerns:

To what extent should the nation marshal resources to deal with the immediate threat -- by stockpiling promising drugs and vaccines, for example, that may prove useless by the time a pandemic occurs?

How much should the nation focus on longer-term efforts such as investing in basic research that could lead to better vaccines that could be tailored quickly to new strains of flu?

And what level of responsibility and risk should be shouldered by private companies, which must satisfy their own financial interests yet are home today to much of the nation's scientific expertise and virtually all of its drug and vaccine production capacity?

The government's long-awaited report provides rough answers, at least, to those and other crucial questions.

More generally, the plan offers a snapshot of the health challenges facing the nation. It highlights the vulnerabilities created by the reduced capacity of the nation's hospitals and first-responder networks, the daunting conundrum of how to care for tens of millions of uninsured people, and the need to improve communication and cooperation with other nations whose health problems once seemed largely irrelevant to Americans.

"Ducks do not respect international boundaries," said Thomas Murray, president of the Hastings Center, a bioethics think tank in Garrison, N.Y., referring to migratory birds now spreading bird flu around the world. "We have to recognize our interdependency with other nations and their public health systems."

In some ways the plan itself was the easy part, experts in public health said yesterday. Still to come is the political process of deciding how to finance its recommendations and what incentives to give private industry to help bolster the nation's biodefenses.

Among the bigger unresolved issues is how to get industry to make substantial investments in new avian flu drugs and vaccines, given the uncertainty of making a profit from the first generation of those products and the liability concerns that always accompany vaccines.

Echoing recent comments from President Bush, for example, the report calls on Congress to pass legislation that would protect vaccine makers from lawsuits resulting from their products' use. But not everyone agrees on enacting such a sweeping provision, several versions of which Congress is expected to consider soon.

George Conk, an expert in product liability at the Fordham University law school in New York, said the need for such protections has been overblown.

Conk pointed to recent research published in the New England Journal of Medicine that documented the very low rate of serious reactions to flu vaccines in the past two decades. The study found that only five deaths and 30 serious reactions were reported for every 10 million doses of flu vaccine given in 1990. More recently those numbers have shrunk to about 15 serious adverse reactions per 10 million doses.

Conk also took issue with proposed legislation supported by the Bush administration that would not only protect vaccine manufacturers but also block any judicial review of the actions of the secretary of health and human services and the attorney general should they declare a public health emergency to facilitate widespread use of a new vaccine.

"Do we really distrust our courts enough that these leaders should not be subject to judicial review?" Conk asked.

Alan Meisel, a professor of law and bioethics at the University of Pittsburgh, wondered whether it was even possible to rely on private industry to take on such a crucial part of the task of protecting the public in an emergency on the scale of a flu pandemic.

When the nation last faced a danger of this scale, he said -- referring to World War II-era concerns that Germany was developing an atomic bomb -- the government did not go to the private sector to see what liability protections and profit margins might be required to make a bomb for the United States.

"I thought the one purpose of government that was inarguable was to take measures for the common good where others could not possibly do so on their own," Meisel said, arguing for a sort of pandemic-flu Manhattan Project.

Federal officials, however, have repeatedly said that the government is not nearly as well equipped as the private sector to develop and mass produce the medical products needed to fight a pandemic.

The degree to which industry will be relieved of risk as it takes on that responsibility is one of many contentious details that will have to shake out in the weeks and months to come.