»Killer Flu Pandemic«

There have been three flu pandemics in the last century, the worst in 1918, which killed more than half a million Americans and 20 million people worldwide.

It's impossible to predict the toll of the next one. But estimates suggest a bad one could kill up to 207,000 Americans, says the nation's new response plan, obtained Wednesday by The Associated Press.

That's almost six times more lives than regular flu claims every year. Millions of sick patients could swarm doctors' offices and hospitals, and the country could suffer an economic and social wallop from disruption of transportation, commerce, even routine public safety.

Scientists who re-created the 1918 Spanish flu say the killer virus was initially a bird flu that learned to infect people. Alarmingly, they find that today's H5N1 bird flu is starting to learn the same tricks.
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"These H5N1 viruses are being exposed to human adaptive pressures, and may be going down a similar path to the one that led to the 1918 virus," Taubenberger said in a news conference. "But the H5N1 strains have only a few of these mutations, whereas the 1918 virus has a larger number."

In 1918-1919, the so-called Spanish flu killed some 50 million people -- including 675,000 Americans. Most of the victims were healthy people in the prime of life.

The researchers’ findings -- published this week in the journals Nature and Science -- come from a remarkable decade-long effort to unlock the secrets of the most deadly flu bug ever known.

To do this, the researchers used a technique called reverse genetics to re-create a living 1918 virus. To do this, they gathered viral DNA from the preserved tissues of people who died in 1918 and 1919 -- including a woman whose body was frozen in the Alaskan permafrost.

The resurrected virus now lives in high-level containment within the CDC. But that's not what worries public health officials.
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The genetic changes that help flu bugs adapt to humans appear to be common to all type A flu viruses.

"What is interesting is these genes seem to be involved in the virulence of other flu viruses, not just bird flu," Garcia-Sastre said at the news conference. "So there are common themes involved in the virulence of flu viruses. Now we have good clues for the development of new drugs against flu disease."
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Gerberding says that everything is being done to ensure that the bug stays in the lab. But if it were to escape, she says it probably would not rekindle a 1918-style epidemic. For one thing, it's an H1N1 virus, and the current annual flu vaccine contains an H1N1 virus. Moreover, most people have been exposed to H1N1 viruses, so many people would be immune.