Age distribution of cases and deaths during the 1889 influenza pandemic.

Using historical data taken from archival records from five European countries and the United States, we evaluate the age distributions of influenza cases and deaths during the 1889 influenza pandemic. We found that the clinical attack rate in 1889 was relatively high and constant between the ages of 1 and 60 years, but was lower outside of the extremes of this age range. By contrast, age-specific influenza-related mortality rates were J-shaped and increased with age beyond 20 years. We conclude that the age-specific attack rates of the 1889 pandemic were most similar to those of the 1968 pandemic and that influenza-related mortality rates did not follow a W-shaped curve as was observed during the 1918 pandemic. Adding 1889 to the short catalogue of influenza pandemics previously studied makes the 1918 pandemic even more exceptional in terms of mortality burden and age distribution of deaths.