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Swine Flu Pandemic FAQ

What the swine flu pandemic means to you.
WebMD Feature
Reviewed by Louise Chang, MD

Swine flu is pandemic, the World Health Organization (WHO) has declared.

The declaration does not mean that swine flu -- aka novel influenza 2009 type A H1N1 -- is any more deadly today than it was yesterday.

Swine Flu Outbreak: Get the Facts

Swine Flu Slideshow

Learn more about the H1N1 swine flu and see what you can do to stay healthy.

View the slideshow.

A pandemic sounds scary. But what does it really mean? Here are WebMD's answers to your questions.

  • What is a pandemic?
  • What does the WHO pandemic alert mean?
  • Why has WHO declared a pandemic now?
  • Has H1N1 swine flu become more dangerous?
  • Am I less safe now that swine flu is pandemic?
  • What should I do now that a pandemic has been declared?
  • When will the pandemic end?
  • What is the government doing about the pandemic?

Questions about swine flu? See WebMD's swine flu FAQ.

What is a pandemic?

A pandemic is a new infectious disease that spreads around the world.

The best recent example of a pandemic is AIDS, caused by a virus new to humans: HIV.

Seasonal flu viruses spread around the globe and cause 250,000 to 500,000 deaths each year -- including some 36,000 annual deaths in the U.S. But seasonal flu isn't considered a pandemic, even though the viruses that cause them change a little from season to season.

One of the seasonal flu viruses is a type A H1N1 virus. But the type H1N1 swine flu virus that appeared in 2009 is an entirely different virus. It carries genes from swine flu viruses from North America and Eurasia as well as genes from human and bird flu viruses.

Humans have never before been infected with this virus. That means that nobody is immune, although some people born before 1957 may have been exposed to an ancestor virus that could possibly give them a small degree of protection.

Because the vast majority of people are vulnerable to the 2009 H1N1 swine flu virus, because it spreads easily from person to person, and because the virus is spreading in communities in different parts of the world, the current swine flu has reached pandemic proportions.

Flu pandemics occur regularly. That's because there are many kinds of flu viruses in animals (mostly birds), but so far only a few have evolved the ability to infect humans. There were three flu pandemics in the 20th century: in 1918, in 1957, and in 1968.

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