How are Seasonal, Avian and Pandemic influenzas different?
Seasonal influenza is a contagious respiratory illness caused by common influenza viruses. Most people have some immunity, and a vaccine is available. Avian influenza (or Bird flu) is caused by avian influenza viruses, which occur naturally among birds. There is no human immunity and no vaccine is available. If human to human transmission occurs, Avian influenza may become a pandemic influenza. Pandemic influenza is a global outbreak that occurs when a new influenza virus causes serious human illness and spreads easily from person to person world-wide. Currently there is no pandemic influenza.
