FIGURE 1——Crude mortality per 100000 population, by influenza season (July to June of the following year), for seasons 1900–1901 to 2003–2004 (a) and 1930–1931 to 2003–2004 (b), United States.
Note. International Classification of Diseases (ICD) revision 1 was used from 1900 to 1909, revision 2 from 1910 to 1920, revision 3 from 1921 to 1929. Comparability ratios are unavailable for revisions 1 to 3. Beginning in 1930, influenza mortality rates have been adjusted for changes in ICD revisions to reflect conditions in the current ICD revision 10.
FIGURE 2——Crude influenza-classed mortality per 100 000 population, by month, for 1900–2004 (a) and 1930–2004 (b), United States.
Note. International Classification of Diseases (ICD) revision 1 was used from 1900 to 1909, revision 2 from 1910 to 1920, revision 3 from 1921 to 1929. Comparability ratios are unavailable for revisions 1 to 3. Beginning in 1930, influenza mortality rates have been adjusted for changes in ICD revisions to reflect conditions in the current ICD revision 10.
FIGURE 3——Comparison of total recorded influenza deaths and current Centers for Disease Control and Prevention (CDC) estimates of influenza-associated mortality for the seasons 1976–1977 to 1998–1999, United States.
Note. CDC influenza-associated mortality estimates are from Table 2 in Thompson et al.4
