So what would a great influenza pandemic be like? There are reports from the 1918 Spanish Influenza, but truthfully its death rate is not high enough in most places to give a true sense to the panic caused by a contagious disease for which there is no resistance [I was incorrect in this statement]. I also wanted something different. It is a little like discussing societal collapse. Everyone knows about the big ones like Rome, or the Mayas, but they generally have no idea about how many other societies collapsed over short periods of time. I wanted an influenza pandemic that was different, but detailed enough to bring home the impact.
Unfortunately there is one group that can be used as an example, and while accounts are hard to find they do exist.
The Native Americans were susceptible to a number of European Diseases. Many of these diseases have vaccines, are eradicated (small box) or rare in the United States (cholera). One of the diseases that they are still susceptible to is influenza: the flu. During the last H1N1 outbreak in 2009, various native indigenous peoples from Australia to Canada to the United States had a 3 to 8 times higher rate of hospitalization and death. Deaths Related to 2009 Pandemic Influenza A (H1N1) Among American Indian/Alaska Natives --- 12 States, 2009, MMWR, December 11, 2009.
During the great Native American die-off, influenza is one of the major killers. But accounts of its effects are often buried in with the many other diseases that they died from. However, I did find one clear account where influenza was the isolated culprit, and it is actually from modern times.