Table 3.

Pandemics of influenza virus infection

Pandemics during nineteenth century	“Asiatic (Russian Flu)” 1889–1890	1 million death, strain H3N8
Influenza pandemics during twentieth century	“Spanish” flu (1918–1919) (devastating pandemic)	Most deadliest pandemic caused by H1N1, >500,000 people died in the United State and up to 50 million people worldwide [70]
	“Asian” flu (1957–1958) (moderate)	Caused by new H2N2 strain and killed two million people [23]
	“Hong Kong” flu (1968–1969) (mild)	Caused by H3N2 strain and killed one million people [25]
Influenza pandemics during twenty-first century	“Swine flu” (2009)	Strain (H1N1), 6770 deaths reported till 16 Nov [7]