The late Joshua Lederberg, a Nobel-winning molecular biologist (at the age of 33!), wrote an essay on the history of our fight against microbes titled "Infectious History." It's readable and covers a lot of ground fairly succinctly, and there's a non-paywalled version here. (The formatting isn't great, so it's a great excuse to install the Readability plugin if you haven't already.) One of my favorite excerpts:
Bacteriology's slow acceptance was partly due to the minuscule dimensions of microbes. The microscopes of the 19th and early 20th centuries could not resolve internal microbial anatomy with any detail. Only with the advent of electron microscopy in the 1930s did these structures (nucleoids, ribosomes, cell walls and membranes, flagella) become discernible. Prior to that instrumental breakthrough, most biologists had little, if anything, to do with bacteria and viruses. When they did, they viewed such organisms as mysteriously precellular. It was still an audacious leap for René Dubos to entitle his famous 1945 monograph "The Bacterial Cell."
And on diminishing returns on extending life expectancy (at least in industrialized countries) since 1950:
Other statistics reveal that the decline in mortality ascribable to infectious disease accounted for almost all of the improvement in longevity up to 1950, when life expectancy had reached 68. The additional decade of life expectancy for babies born today took the rest of the century to gain. Further improvements now appear to be on an asymptotic trajectory: Each new gain is ever harder to come by, at least pending unpredictable breakthroughs in the biology of aging.
Read the rest. I came across Lederberg's article in a footnote to Adel Mahmoud's article "A global road map is needed for vaccine research, development, and deployment."