Until now, the fastest vac­cine ever made — for mumps — took four years. And while our cur­rent effort to devel­op a covid-19 vac­cine involves thou­sands of peo­ple work­ing around the clock, the mumps vac­cine was devel­oped almost exclu­sive­ly by one per­son: Mau­rice Hille­man. Hille­man cranked out more than 40 oth­er vac­cines over the course of his career, includ­ing 8 of the 14 rou­tine­ly giv­en to chil­dren. He arguably saved more lives than any oth­er sin­gle per­son. And through his work, Hille­man embod­ied the instincts, dri­ve, and guts it takes to mar­shall the human body’s defens­es against a dis­ease. But through him we also see the strug­gle and the costs of these mon­u­men­tal sci­en­tif­ic efforts.