There has been a recent study of the 1918-1919 flu. It turns out that the pandemic affected health outcomes for many decades to follow. Here is the abstract:
In the 1960-1980 Decennial U.S. Census data, cohorts in utero during the height of the Pandemic typically display reduced educational attainment, increased rates of physical disability, lower income, lower socioeconomic status, as well as accelerated adult mortality compared with other birth cohorts. In addition, persons born in states with more severe exposure to the Pandemic experienced worse outcomes than those born in states with less severe Pandemic exposures. These results demonstrate that investments aimed at improving fetal health can have substantial long-term effects on subsequent health and economic outcomes.
Thanks to Alex Tabarrok for the pointer, his post contains a lengthier and interesting discussion of the 1918-1919 pandemic.