Two million dead. Hospitals overwhelmed. Schools closed. Swaths of empty seats at baseball stadiums and houses of worship. An economic recovery snuffed out.

The world is not remotely close to what U.S. government planners are considering a worst-case scenario: a global pandemic. Government leaders at all levels, and major American employers, have spent almost four years planning for a pandemic in series of exercises. Their reports, reviewed by The Associated Press, and interviews with participants paint a grim picture of what could happen if the swine flu should get severely out of control.

A full-scale pandemic, should it ever come, could be expected to claim the lives of about 2 percent of those infected, or about 2 million Americans.

The government estimates that a pandemic like the 1918 Spanish flu would sicken 90 million Americans, or about 30 percent of the population. Of those, nearly 10 million would have to be admitted to hospitals, and nearly 1.5 million would need intensive care. About 750,000 would need the help of mechanical ventilators to keep breathing.

No one would be immune from the consequences, even those who do not get sick, according to worst-case exercises run by local and national agencies.

Schools would be closed to try and block the spread of illness, for example, but school buses might be needed to take flu victims to alternative clinics rather than overcrowded hospitals.

A 2006 report in the Washington region found both Maryland and Virginia would run out of hospital beds within two weeks of a moderate outbreak.

People who get sick would be isolated, and their relatives could be quarantined.

But even if families were not required to stay home, many would do so to take care of sick relatives or because they were afraid of getting sick themselves.

Hotels, restaurants and airlines face loss of business as business travel and meetings would be replaced by teleconferences.

In the cities, commuters who do go to work might bike or walk instead of using transit.

In 1918, authorities even urged churches to cancel services, to the chagrin of some pastors.

Society as a whole would go into a defensive crouch, and that would deliver a shock to the economy.

The Trust for America's Health, an independent public health group, estimated in 2007 that a severe pandemic would shrink U.S. economic output about 5.5 percent.

Take a breath. Even if the new swine flu from Mexico should turn out to be especially aggressive, the worst consequences could be averted.

Although some U.S. states are less prepared than others, the nation has stockpiled antiviral medicines, speeded the production of vaccines, and laid down basic public health guidelines.

Homeland Security Secretary Janet Napolitano said Monday that the United States is preparing as if the swine flu outbreak were a full pandemic. It is not at that stage and may never reach it.

Disease detectives are following a series of outbreaks, of varying severity, all of which appear to be related to Mexico. A pandemic would spread throughout the world with explosive speed.

The government got serious about worst-case planning during the 2005 bird flu scare, partly as a result of the grossly unprepared state of relief agencies after the August 2005 monster Hurricane Katrina, which destroyed large sections of historic New Orleans, Louisiana.

"We have a playback that was developed and is being followed," said Michael Leavitt, who as secretary of Health and Human Services oversaw pandemic planning for President George W. Bush. "It's a substantially better picture than what we faced three years ago."

———

On the Net:

U.S. government flu Web site http://www.pandemicflu.gov