One of the most important tools in the public health arsenal, vaccines are to thank for the global eradication of smallpox, and for allowing us to defeat the dire threat of infectious disease for more than one hundred years. Vaccine development is where scientists turn when faced with the frightening spread of new diseases like Zika, SARS, and Ebola. So if vaccines have proven to be such an effective tool, why are growing numbers of people questioning the wisdom of vaccinating children? Why have public-sector vaccine producers almost vanished? And can we trust the multinational corporations...