Table 5.

Antigenic subtypes of influenza A viruses that naturally infected man (based on various data presented above).

Antigenic subtype	Mode of occurrence	Place of occurrence
H1N1	Pandemic	Worldwide
H2N2	Pandemic	Worldwide
H3N2	Pandemic	Worldwide
H2N8	Pandemic	Worldwide
H3N8	Pandemic	Worldwide
H1N2	Epidemic (in 2001); sporadic	America, Asia, and Europe
H1N3	Singular	Azerbaijan
H5N1	Sporadically ongoing	Eastern Hemisphere
H7N2	Singular	USA
H7N3	Singular	Canada
H7N7	Limited epidemic	The Netherlands
H7N7 (further cases)	Singular	UK, USA (seal originated)
H9N2	Sporadic	China, Hong-Kong, and Bangladesh
H10N7	Singular	Egypt