Science
1.8 million children took part in history's largest medical field trial
The 1954 trial of Jonas Salk's polio vaccine enrolled 1.8 million American schoolchildren, run by 325,000 volunteer doctors, nurses and citizens with no government or pharmaceutical funding. It was among the first large trials to use double-blind, placebo-controlled design, so neither families nor doctors knew who'd gotten the real vaccine. A year later it was declared safe and effective, and polio cases collapsed within years.