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. Author manuscript; available in PMC: 2010 Jan 16.
Published in final edited form as: N Engl J Med. 2009 Jun 29;361(3):225–229. doi: 10.1056/NEJMp0904819

Table. Mortality Associated with Influenza Pandemics and Selected Seasonal Epidemic Events, 1918-2009*.

Years Circulating Virus (Genetic Mechanism) Excess Deaths from Any Cause no. per 100,000 persons/yr
1918-1919 H1N1 (viral introduction), pandemic 598.0
1928-1929 H1N1 (drift) 96.7
1934-1936 H1N1 (drift) 52.0
1947-1948 H1N1 A’ (intrasubtypic reassortment) 8.9
1951-1953 H1N1 (intrasubtypic reassortment) 34.1
1957-1958 H2N2 (antigenic shift), pandemic 40.6
1968-1969 H3N2 (antigenic shift), pandemic 16.9
1972-1973 H3N2 A Port Chalmers (drift) 11.8
1975-1976 H3N2 (drift) and H1N1 (“swine flu” outbreak) 12.4
1977-1978 H3N2 (drift) and H1N1 (viral return) 21.0
1997-1999 H3N2 A Sydney (intrasubtypic reassortment) and H1N1 (drift) 49.5
2003-2004 H3N2 A Fujian (intrasubtypic reassortment) and H1N1 (drift) 17.1
2009 H3N2 and H1N1 (drift) and swine-origin H1N1 (viral introduction), pandemic ?
*

Mortality data include deaths associated with all influenza A and B viruses combined. Many of these data have been calculated with the use of differing methods and may not be strictly comparable.1,2 The 1934, 1951, and 1997 data span 2 years.