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Table 1 Influenza pandemics since the 20th century

From: Novel swine-origin influenza A virus in humans: another pandemic knocking at the door

Year Virus subtype Deaths (estimated) Reassortment
1918/1919
“Spanish flu”
H1N1 50 million All segments of avian origin
1957–1963
“Asian flu”
H2N2 2–4 million Five segments of H1N1 + PB1, HA, NA of avian origin
1968–1970
“Hong Kong flu”
H3N2 1–2 million Six segments of H2N2 + PB1, HA of avian origin
1977–1979
“Russian flu”
H1N1 0.7 million Identical with “Spanish flu” virus
2009–?
Swine-origin influenza A virus
H1N1 ? Three segments of classis swine North America, two segments avian North America, one segment H3N2, two segments Eurasian swine lineage