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CDC develops system to gauge severity of pandemic

WASHINGTON—As scientists renewed their warnings about the possibility of a deadly worldwide flu epidemic, federal health officials on Thursday introduced a new system to gauge the severity of an outbreak and to help communities deal with the impending threat.

The "pandemic severity index," developed by the Centers for Disease Control and Prevention, ranks flu outbreaks in terms of expected deaths and is modeled after the hurricane warning system that the National Weather Service uses.

In addition to weighing the risks of a potential outbreak, the new system advises local leaders about when and how long to close schools, quarantine family members and keep people home from work if necessary.

The mildest flu strains, those expected to kill fewer than 90,000 Americans, would be known as Category 1 outbreaks. The most severe, a Category 5 flu epidemic, could kill more than 1.8 million U.S. residents. State and local leaders would adjust the precautions they take according to the rankings, which the CDC will issue.

The rating system is a key feature of a 108-page manual that'll help standardize the public health measures that state and local leaders will take. The document outlines a series of preventive measures designed to delay the onset of an outbreak, reduce the subsequent burden on hospitals and minimize the number of resulting deaths and illnesses.

"Pandemic influenza is not necessarily imminent, but we believe it's inevitable. And it's not a question of if, it's a question of when, so we do have to prepare," said CDC Director Julie Gerberding. "We would be irresponsible if we didn't continue our planning efforts."

The new CDC initiatives come as 350 of the world's top flu experts heard a sobering report Thursday on the continuing threat of a pandemic. Speakers at a conference in Arlington, Va., reported that neither the United States nor the world is prepared to meet the danger posed by the lethal H5N1 avian flu virus.

The H5N1 virus has spread to 50 countries in Asia, Africa and Europe, and it has infected 230 million birds. To date, 270 humans have contracted the virus and 164 have died. In the past two weeks, seven cases have been reported, with five deaths.

"As we speak, we're seeing a new upsurge of infections and human cases in Indonesia, Egypt and Nigeria," said David Nabarro, the United Nations coordinator for avian and human influenza.

"The disease is highly pathogenic and continues to spread. That's why we continue to take this threat so seriously," said Michael Leavitt, secretary of the Department of Health and Human Services.

The federal government has stockpiled enough antiviral drugs to treat more than 22 million people. Another 13 million treatments are set to arrive in March.

The CDC's new protective strategies include isolating and treating all flu sufferers with antiviral medications at home and in health-care settings for seven to 10 days. Voluntary seven-day home quarantines—with possible antiviral treatments—also are recommended for household members with confirmed or probable influenza infections.

The CDC also calls for closing schools, colleges and daycare centers for up to three months while reducing social contact among young people. The agency also recommended on-the-job and community precautions, such as canceling public gatherings and expanding workplace leaves.

Depending on the severity of the flu strain and outbreak, some or all of the protective measures should be implemented locally at the first confirmed case of pandemic influenza, Gerberding said.

Use of all the precautions are urged only for Category 4 and Category 5 outbreaks. The 1918 flu outbreak would be considered a Category 5 outbreak, while the 1967 and 1968 flu strains would be Category 2 outbreaks, said Dr. Marty Cetron, director of the CDC's Division of Global Migration and Quarantine.

Severe precautions, such as school closings, likely wouldn't be needed in milder outbreaks, "but these steps may save lives during severe pandemics," the document reads.

A flu pandemic occurs when a new influenza virus emerges, people have little or no immunity to it, and there's no vaccine for it.

Implementing the new CDC precautions would cause worker absenteeism to soar as adults care for sick children or those forced to remain home because of school closures, experts said.

A three-month Category 5 pandemic flu outbreak would cost the U.S. economy $625 billion—about 5 percent of the gross domestic product—as employers struggle with absenteeism, lost production and a sharp decline in consumer spending, according to the Congressional Budget Office.

The CBO estimated that 30 percent of the American population would become ill in a three-month Category 5 outbreak and about one-third of the U.S. workforce would miss three weeks of work. The economic impact, driven in part by fear and confusion, would be equivalent to a recession.

The CDC guidelines highlight the need for intensive local pandemic planning and preparation, said Patrick Libby, the executive director of the National Association of State and County Health Officials, which represents 2,800 health departments nationwide.

"You can't just throw a switch and assume everybody's going to fall into line," Libby said. "You've got to be doing the groundwork now," working with schools, businesses, hospitals and local governments to make sure each is prepared when precautionary measures are called for.

Labor officials are eyeing whether incentives such as short-term unemployment compensation would help employees remain home during a pandemic outbreak.

For more information about pandemic flu planning, go to To view the new CDC guidance document, go to


(McClatchy Newspapers correspondent Robert S. Boyd contributed to this report.)


(c) 2007, McClatchy-Tribune Information Services.

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