3 ms·

The 1918 flu particularly affected 20-40 year old healthy people. https://www.smithsonianmag.com/history/why-did-1918-flu-kill-so-many-otherwise-healthy-young-

• jacquesm 7y ago
  That was an anomaly in many other ways too. Keep in mind that a good chunk of the world was still recovering from WWI. Being exposed to some other disease earlier in life can give a similar effect to vaccination. This is one of the reasons why HIV spread was not as bad as it could have been in Western Europe where exposure to a disease still gave some benefits many centuries later: https://www.nature.com/news/2005/050307/full/news050307-15.html https://www.nature.com/news/2005/050307/full/news050307-15.h...