Asian flu of 1957, also called Asian flu pandemic of 1957, outbreak of influenza that was first identified in February 1957 in East Asia and that subsequently spread to countries worldwide. The 1957 Asian flu was the second major influenza pandemic to occur in the 20th century; it followed the influenza pandemic of 1918–19 (also known as Spanish flu) and preceded the Hong Kong flu pandemic of 1968. The Asian flu outbreak caused an estimated one million to two million deaths worldwide and is generally considered to have been the least severe of the three influenza pandemics of the 20th century.