A century of innovation in vaccines.

Surveying a century of vaccinology, the author sifts through three discrete eras and briefly examines some of the major factors accelerating and constraining the process of innovation. From the 1890 s through the 1930 s, most of the expectations generated by the scientific networks of the late nineteenth century were unfulfilled. During the next forty years, however, vaccinology experienced an astonishing era of innovation in vaccine discovery, development, and distribution. This golden age was followed, however, by the great paradox of our times: while the scientific opportunities have never been greater, there have been and continue to be serious threats to the viability of the three sets of institutions in the networks sustaining vaccine innovation.