How Does Seasonal Flu Differ From Pandemic Flu?

Seasonal Flu

1. Outbreaks follow predictable seasonal patterns; occurs annually, usually in winter, in temperate climates.

2. Usually some immunity built up from previous exposure

3. Healthy adults usually not at risk for serious complications; the very young, the elderly and those with certain underlying health conditions at increased risk for serious complications

4. Health systems can usually meet public and patient needs

5. Vaccine developed based on known flu strains and available for annual flu season

6. Adequate supplies of antivirals are usually available

7. Average U.S. deaths approximately 36,000/yr

8. Symptoms: fever, cough, runny nose, muscle pain. Deaths often caused by complications, such as pneumonia.

9. Generally causes modest impact on society (e.g., some school closing, encouragement of people who are sick to stay home)

10. Manageable impact on domestic and world economy



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Pandemic Flu

1. Occurs rarely (three times in 20th century - last in 1968)

2. No previous exposure; little or no pre-existing immunity

3. Healthy people may be at increased risk for serious complications

4. Health systems may be overwhelmed


5. Vaccine probably would not be available in the early stages of a pandemic

6. Effective antivirals may be in limited supply

7. Number of deaths could be quite high (e.g., U.S. 1918 death toll approximately 675,000)

8. Symptoms may be more severe and complications more frequent

9. May cause major impact on society (e.g. widespread restrictions on travel, closings of schools and businesses, cancellation of large public gatherings)

10. Potential for severe impact on domestic and world economy

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