Original: The serotypes that have been confirmed in humans , ordered by the number of known human pandemic deaths , are : H1N1 caused '' Spanish Flu '' in 1918 , '' Swine flu '' in 2009 H2N2 caused '' Asian Flu '' .
Simplified: The serotypes that have been confirmed in humans , ordered by the number of known human pandemic deaths , are : H1N1 caused '' Spanish Flu '' .