When a pandemic isn't a pandemic

ATLANTA, Georgia (CNN) -- When the World Health Organization raised its influenza pandemic alert from a Phase 4 to a Phase 5 last week, there was a bit of a gasp heard round the world.

After all, Phase 5 "is a strong signal that a pandemic is imminent," according to WHO.

"All countries should immediately activate their pandemic preparedness plans," the organization's director-general, Dr. Margaret Chan, said Wednesday. "After all, it really is all of humanity that is under threat during a pandemic."

But the word "pandemic" isn't quite as scary as it sounds, explained David Ozonoff, professor of environmental health at the Boston University School of Public Health.

"When people hear the words 'pandemic' and 'flu,' the first thing that comes to mind is 1918, which was a real horror show," Ozonoff said, referring to the flu pandemic that killed some 50 million people 91 years ago.

But you can have a pandemic without a large number of deaths, he said."The word pandemic refers to how widely dispersed a disease is, not to how severe the disease is," he said

Confusion about the meaning of "pandemic" is understandable, Ozonoff said, considering the definition of the word is "not set in stone."

Until Monday morning, the WHO had a definition on its Web site saying that a pandemic flu causes "enormous numbers of deaths and illness." After a CNN reporter pointed this out, WHO spokeswoman Natalie Boudou called back to say the definition was in error and had been pulled from the WHO Web site.

"It was a mistake, and we apologize for the confusion," she said. "(That definition) was put up a while ago and paints a rather bleak picture and could be very scary."

The correct definition is that "pandemic" indicates outbreaks in at least two of the regions into which WHO divides the world, but has nothing to do with the severity of the illnesses or the number of deaths.

Based on lessons from the past, "influenza may cause mild disease in affluent countries, but more severe disease, with higher mortality, in developing countries," Chan said at Wednesday's news conference.

There have been three influenza pandemics in this century, said Andrew Pekosz, associate professor of microbiology and immunology at Johns Hopkins University's Bloomberg School of Public Health. The other two, in 1957 and 1968, also were caused by new viruses to which no one had immunity, but didn't cause nearly the number of deaths as the one in 1918.

"I think people need to be reminded that this current H1N1 outbreak is going to resemble much more the pandemics in 1957 and 1968, where there was an increase in deaths from other years, but nothing like the millions of deaths we saw in 1918," Pekosz said.

My comment

The news gave a clear definition of the word " pandemic" which might not refer to severe death but a virus that disperse widely. The news compared H1N1 flu with the pandemic in 1918 and 1957. While the swine flu is similar to 1957 which is also cause by new virus, the pandemic in 1918 is worse than swine flu. Once we understand the meaning of the word, we may not act too exaggeratedly to this outbreak. 

Since Taiwan have experienced SARS in 2003, our government and people took action earilier than other places or countries which I feel much confident and less scared the spread of the swine flu.  But still, I would not forget how SARS impacted me. I In 2003, I had to take the entrance exam for senior high school and the exam was delayed very late because of SARS. Many teenagers in my age had to studied and waited for the exam. I was not happy in that time. I felt stressful.