You are bringing up one of the biggest holes in modern understanding of history, lack of data. For example, tuberculosis was on the decline for a very, very lo

You are bringing up one of the biggest holes in modern understanding of history, lack of data. For example, tuberculosis was on the decline for a very, very long time before any medical solution was found, and it was nearly irradiated before there was a vaccine. [0] The vaccine had almost no effect on TB's decline in society. This graph is nearly identical to all diseases that I looked up. Good housing, nutrition, cleanliness are the biggest cures for disease. [0] https://en.wikipedia.org/wiki/File:Tuberculosis_in_the_USA_1861-2014.png https://en.wikipedia.org/wiki/File:Tuberculosis_in_the_USA_1...