...viruses have fascinated me ever since...

The John Barry book is one everyone should read. Do be aware that in it he postulates that the influenza actually got started in Kansas. Since then, research has shown that it probably did not, and Barry himself agrees.

Another fascinating thing about that book is that it covers how the training of doctors was undergoing a fundamental change at that time. Before, American physicians were for the most part very poorly trained. At the end, not long after WWI, we had pretty much the best medical education in the world.

I read as much as I can lay my hands on about disease and epidemiology. Plagues and Peoples by William H. McNeill is an excellent starting point. I do have a copy of it that I've been meaning to reread for some time. McNeill only died in 2016. He was 98 years old.

Very interesting. I find that I can't learn enough about this. It fascinates me. Scares me as well.