Flu Definitions: Between Seasonal, Avian and Pandemic Flu, each are very different.
“Common” Seasonal Flu: A contagious viral respiratory illness which the majority of people have some immunity to. Various vaccines exist.
Avian “Bird” Flu : Born out of naturally occurring wild bird influenza viruses, the variant H5N1 can transmit to people, as people currently do not have immunity and a vaccine does not exist.
Pandemic Flu: Due to a lack of natural immunity, a virulent flu which spreads easily from human to human and causes serious illness on a global scale.