A public health expert familiar with the latest draft of the federal government's pandemic influenza preparedness plan said it predicts that a full-scale disease outbreak might kill as many as 1.9 million Americans and sicken more than half the country's population.

The military probably would be used to help move critical supplies and provide security at places such as vaccination centers, the expert said, but quarantines will play only a small role in a pandemic response. Many crucial decisions on how to manage disruptions and shortages will be made at the local, not national, level.

Michael T. Osterholm, who advised the Department of Health and Human Services from 2000 to 2003 and now heads a medical think tank in Minnesota, made the comments after an article on the government's proposal appeared in the New York Times yesterday. The article described a 381-page version of the plan dated Sept. 30.

"There have been tremendous improvements in the plan even over the last week to 10 days," Osterholm said. In particular, he said, the most recent version emphasizes the likely prolonged effects of a flu pandemic and the need for unprecedented cooperation between the government and the business sector for more than a year.

"It is very much in flux now," he said. "Up until recently, it has been a plan that was handling this [event] much more like an earthquake or a hurricane. But it is not something that occurs over a very short period of time and then we go into the recovery phase. A pandemic will literally unfold, like a slow-moving tsunami, over 12 to 18 months."

Federal officials refused to provide the latest version or to describe it in any detail. Several of the people most involved in the multi-year writing of the plan were traveling to Southeast Asia yesterday with Health and Human Services Secretary Mike Leavitt and were unavailable.

Leavitt will visit at least four countries where influenza A/H5N1 -- also known as "bird flu" -- has killed or led to the culling of 140 million birds, as well as to 116 human cases and 60 deaths. Accompanying him on the 10-day trip are Jong Wook Lee, director general of the World Health Organization, and Margaret F.C. Chan, WHO's chief of pandemic influenza planning.

The trip's purpose, Leavitt said before departing, was to "emphasize the importance of this issue for the United States" and to stress the "need for the world community to be transparent and cooperative" in disease surveillance and reporting.

The final version of the pandemic preparedness plan is unlikely to be released until Leavitt returns. An HHS spokeswoman, Christina Pearson, said, "it's totally premature" to release the document now.

"We're still getting comments on the plan," she said. Speaking generally, she said that "it outlines the public health and health care responses. It describes things communities should be doing now. It has to be a foundation for further efforts."

Osterholm confirmed this view, although he would not give specific details about the plan.

"Basically, cities and states are going to have to shoulder a lot of this burden of response on their own. There is no other choice. When you have all 50 states, every major city, every county and every hospital in crisis -- the federal government can't address all of that," Osterholm said. "Every place is going to need resources and expertise at the same time, and in fact every country in the world is going to need those things."

In describing what Osterholm called "the upper bounds of what a pandemic could look like," the plan describes potential shortages of medicines for non-influenza illnesses, disruptions in the delivery of food and conceivably a lack of caskets and crematorium space.

Among the many critical supplies that hospitals and localities would need to have are masks, gloves and other protective equipment for nurses, physicians and first responders, who would be expected to have exposure month after month to people ill with influenza. They would be expected to be among the first to get access to short supplies of vaccine against a pandemic flu strain, or to prophylactic drugs.

At his news conference last week, President Bush said troops might be called upon to enforce quarantines during a flu pandemic.

Osterholm said yesterday he thinks "the plan is clearly going to address the role of the military for basic logistical operations, such as moving supplies, to possibly corpse management and possibly security." However, he said, "HHS has heard loud and clear from public health experts that quarantine plays a very limited role in stopping or even slowing influenza."

The forced isolation of citizens, he added, would occur only in particular circumstances, such as when an airplane arrives with potentially infected passengers.

Despite the sketchiness of details about it, the plan immediately became a vehicle for some Democratic leaders to criticize the Bush administration.

"The tragedy that unfolded before and after Katrina revealed how ill-prepared the administration was to deal with natural disasters. With the long-overdue release of their draft plan on avian flu, the administration acknowledged it is also woefully unprepared for yet another type of natural disaster," Senate Minority Leader Harry M. Reid (D-Nev.) said yesterday.

"Democrats recognized this problem months ago. That is why we led the fight to secure nearly $4 billion to help this nation prepare for and respond to an avian flu pandemic," Reid said.

Philip K. Russell, a former senior consultant to HHS's Office of Public Health Emergency Preparedness, said yesterday that "considering previous administrations were unable to agree on and produce a plan in spite of trying since about 1990, this is real progress." He added he thinks "the real reason that we are not ready relates to the vaccine industry and the lack of an aggressive vaccine development, domestic manufacturing and deployment capacity. Maybe this will generate the resources to fix the problem."