How Is Pandemic Flu Different from Seasonal Flu? | Pandemic Influenza (Flu) | CDC

How Is Pandemic Flu Different from Seasonal Flu? | Pandemic Influenza (Flu) | CDC

Seasonal Flu versus Pandemic Flu

​While seasonal flu happens each year, pandemic flu rarely happens. An influenza pandemic is a global outbreak of a new influenza A virus that is very different from current and recently circulating human seasonal influenza A viruses. Only four flu pandemics have occurred in the past 100 years.