Skip to content

Cold, Flu, & Cough Health Center

What Is a Pandemic?

Confused about what a pandemic is versus an epidemic? WebMD explains.
Font Size
A
A
A
By
WebMD Feature

"Pandemic flu" has been one of the buzzwords of late 2005. But how does the phrase that's on everyone's lips differ from "epidemic," that other well-worn disease term?

Apparently, a lot of people aren't sure. Merriam-Webster reports that "pandemic" is the seventh most frequently looked-up word in its online dictionary this year. The definition: "occurring over a wide geographic area and affecting an exceptionally high proportion of the population."

Recommended Related to Cold & Flu

How To Stay Well (When Everyone Else Is Sick)

By Janis Graham 'Tis the season...for colds, flu, stomach bugs, and all those other ills that spread when people come together — whether by choice (at holiday parties) or circumstance (on airplanes). But don't start calculating your sick days just yet. This year you can do more than wash your hands and cross your fingers. Recent research, some of it sparked by the scary H1N1 influenza pandemic of 2009, has uncovered new steps you can take to protect yourself and your family. Most...

Read the How To Stay Well (When Everyone Else Is Sick) article > >

This is almost the same as the dictionary definition for "epidemic," and it doesn't explain much when it comes to influenza -- a.k.a. the flu.

An epidemic of influenza is different from the dreaded pandemic that scientists and world health officials fear is nigh. We might see an epidemic of seasonal influenza during any given year. In fact, we just had one.

Flu reached epidemic levels in the U.S. for 10 weeks in a row during the 2004-2005 season. Records kept by the CDC show that during the week ending March 5, 2005, 8.9% of all deaths reported in 122 U.S. cities were due to influenza and pneumonia (a common complication of the flu).

The CDC's definition of a flu epidemic relates to the percentage of deaths in a given week caused by influenza and pneumonia. The "epidemic threshold" is a certain percentage above what is considered normal for that period. The normal level, or baseline, is statistically determined based on data from past flu seasons.

Christine Pearson, a spokeswoman for the CDC, cautions that the definition of an influenza epidemic doesn't apply to other diseases.

Seasonal flu epidemics may sicken millions, but those who die are typically a small number of the elderly, very young children, and people with weak immune systems. That's not the case during the worst influenza pandemics.

There are two main features of an influenza pandemic. First, the virus is a new strain that has never infected people before. Second, it's on a global scale. Sometimes it's also unusually deadly.

"A pandemic is basically a global epidemic -- an epidemic that spreads to more than one continent," says Dan Epstein, a spokesman for the Pan American Health Organization, a regional office of the World Health Organization.

Influenza pandemics have struck about three times every century since the 1500s, or roughly every 10-50 years. There was one in 1957-1958 and one in 1968-1969. The most infamous pandemic flu of the 20th century, however, was that of 1918-1919. An estimated 40 million people died in less than a year, and what made it so different from seasonal flu epidemics is that it killed primarily young people, those aged 20-45.

1 | 2 | 3

Today on WebMD

hot toddy
15 tips to help you feel better.
man sneezing into elbow
Do echinacea and vitamin C really help a cold?
 
teen girl coughing
Get a good night’s rest with these remedies.
elder berry
Eat these to fight colds, flu, and more.
 
Natural Cold Flu Remedies Slideshow
Slideshow
cold weather
VIDEO
 
Allergy And Sinus Symptom Evaluator
Article
Boy holding ear
Slideshow
 

Loaded with tips to help you avoid food allergy triggers.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.

Thanks!

Now check your email account on your mobile phone to download your new app.

woman receiving vaccine shot
Article
woman with fever
Article
 
Waking up from sleep
Article
woman with sore throat
Slideshow