This is not the first time that passive serotherapy has been described as “miraculous.” These headlines hearken back to well over a century ago, decades before the advent of such miracle drugs as sulfonamides and antibiotics. Medical scientists and practitioners did not wait for such unknown drugs. Rather, if the 1870s and 1880s represented the golden age of microbiology, as Louis Pasteur and Robert Koch led in identifying the agents of anthrax, diphtheria, pneumonia, tuberculosis, and the like, then the 1880s and 1890s represented the advent of applied humoral immunology. By 1890, Emil von Behring and Shibasaburo Kitasato, working under Koch in Berlin, had identified humoral factors in exposed animals that when transferred into laboratory animals were protective against diphtheria and tetanus toxins. From the 1890s onward, this model of production—expose an animal (such as guinea pig, rabbit, cow, or horse) to an identified microbial pathogen, generate antibodies (or use convalescent serum from former patients), and then “passively” transfer the preformed antibodies to an exposed animal or person—could be expanded to such feared and prevalent diseases as pneumococcal pneumonia and meningococcal meningitis.