I've been immersed in 1918 for about a year now, working on a novel about the Pandemic Flu.
The pandemic flu of 1918-1919 killed more people worldwide than the Great War, WWI. Estimates vary, but it's believed about 100 million people died of this virulent plague, and very possibly even more than that because many deaths went unreported.
An influenza epidemic usually results in higher mortality at the beginning and end of the age spectrum: infants and small children, and the elderly. This flu was different and completely unexpected as most of the fatalities were in the 20 to 40 years of age group.
People in their prime of life.
If you go back into your own family history it's quite possible you have an ancestor who died in this pandemic. Or if you happen to be in an old cemetery and see many deaths in the same family in 1918, again, it's quite likely the flu killed them.
The scary thing about the Pandemic Flu is that it will happen again.