Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. H2N2 is a subtype of the species influenzavirus A (sometimes called bird flu virus). H2N2 has mutated into various strains including the Asian Flu strain (now extinct in the wild), H3N2, and various strains found in birds. It is also suspected of causing a human pandemic in 1889. The geographic spreading of the 1889 Russian flu have been studied and published.