
The Spanish Influenza in 1918 killed an estimated 40-50 million people.
The next pandemic in 1957; the Asian influenza caused around 2 million deaths.
The most recent pandemic in 1968, the Hong Kong influenza killed approximately 1 million people.
Between 1997 and 2006 several new strains have appeared: H5N1, H9N2, H7N2, H7N3 and H10N7, all of which have pandemic potential.