Washington ? President Bush’s plan for dealing with a flu pandemic warns that the federal government won’t be able to bail out communities reeling from illness and economic upheaval, and calls on businesses and individuals to take steps now to keep vital services running.

The updated plan, released Wednesday, stresses basic human needs such as medical care and food, but doesn’t address some major hurdles – how to meet those needs if massive absenteeism stops transportation by closing oil refineries, or crashes the Internet so workers can’t telecommute.

“Our efforts require the participation of, and coordination by, all levels of government and segments of society,” Bush said in a letter to Americans unveiling his updated national pandemic response strategy.

“No less important will be the actions of individual citizens, whose participation is necessary to the success of these efforts.”

Influenza pandemics strike every few decades when a never-before-seen strain arises. It’s impossible to predict when the next will occur, or its toll. But last fall, amid concern that the Asian bird flu might lead to one if it starts spreading easily from person to person, Bush proposed a $7.1 billion, multi-year strategy to prepare for the next pandemic.

At the plan’s core: stockpiling enough bird-flu vaccine for 20 million people, plus anti-flu medications and other key medical supplies, to provide some protection while manufacturers race to brew a pandemic-specific inoculation.

Wednesday’s report updates Bush’s initial plan, outlining exactly which government agency is responsible for some 300 additional tasks. It also provides details, beyond health care, of changes Americans could expect in how they travel, work and conduct day-to-day activities during a severe pandemic.

Assistant to the President for Homeland Security and Counterterrorism Frances Townsend briefs the media on their bird-flu response plan, Wednesday, May 3, 2006, in Washington. The plan catalogs steps that the government, businesses and citizens should take if a deadly strain reaches U.S. shores.

The report’s big message: “Local communities will have to address the medical and nonmedical impacts of the pandemic with available resources.” That’s because the federal government won’t be able to offer the kind of aid expected after hurricanes or other one-time, one-location natural disasters, it says.

U.S. borders won’t be sealed after outbreaks abroad, the report says. That would fail to keep out a pandemic – people can spread flu a full day before they show symptoms. Instead, the goal will be to slow influenza’s march, starting by screening international travelers for signs of infection and quarantining possibly ill passengers.

As U.S. infections mount, people will be asked to stay away from crowds, and cancel nonessential travel. Patients’ families would be temporarily isolated. Schools in affected communities would close.

Employers would be urged to let people telecommute, regularly clean buildings – flu viruses can live on hard surfaces for 48 hours – and advise workers to avoid shaking hands and stand 3 feet apart, out of sneeze range.

By assuming a worst-case scenario – up to 2 million U.S. deaths, and up to 40 percent of the work force off the job for several weeks – the government hopes to have enough contingency plans to limit social and economic chaos if a severe pandemic strikes, and to energize private sector preparations.

A recent Associated Press-Ipsos poll found only one in 10 Americans was doing anything to plan for an outbreak.