Wonderful explanation of the development of vaccines and the theory behind them. There is also quite a bit of background on viral and bacterial diseases. The book focuses on Maurice Hilleman, with just the right amount of his personal history to stay interesting without speculation or becoming too personal. Growing up with vaccines, I hadn't realized until reading this book how new they are or how crude the methods of making them were until very recently. The diseases and their impacts are also forgotten or never even known in my generation. There are a surprising number of vaccines now. This book covers so much scientific history that the head spins, especially in chapter 7. It can be hard to keep up with the names and places. Maybe there could be a little less background on some of the scientists, in the interest of not having a reader totally lose track of where they are. Towards the end, there is a synopsis of the vaccine-autism link controversy, fortunately for me, since I had not followed it and could use a complete overview.