How scientists saved humanity from the deadliest infectious diseases--and what we can do to prepare ourselves for future epidemics. After the unprecedented events of the COVID-19 pandemic, it may be hard to imagine a time not so long ago when deadly diseases were a routine part of life. It is harder still to fathom that the best medical thinking at that time blamed these diseases on noxious miasmas, bodily humors, and divine dyspepsia. This all began...