On April 26, 1954, six-year-old Randy Kerr stood first in line at his elementary school gymnasium in McLean, Virginia, sporting a crew cut and a smile. With assembly-line precision, a nurse rolled up his left sleeve, a doctor administered the injection, a clerk recorded the details, and the next child stepped into place. “I could hardly feel it,” boasted Kerr, America’s first polio pioneer. “It hurt less than a penicillin shot.”

This procedure would become nationally routine in the coming weeks as more than a million children took part in the Salk poliomyelitis vaccine trials of 1954, the largest public health experiment in American history. National attention would be riveted on the outcome, with news coverage rivaling the other big stories from that remarkable spring—the Army-McCarthy hearings, the Supreme Court’s decision in Brown v. Board of Education, and the stunning French defeat at Dien Bien Phu. Jonas Salk’s picture adorned the cover of Time magazine. A Gallup poll showed that more Americans were aware of the polio vaccine trials than knew “the full name of the President of the United States.” Never before, it appeared, had the nation been as captivated by the pursuit of a medical or scientific objective.

Such fascination was understandable: by the 1950s, polio had become America’s most dreaded infectious disease, as it fell cruelly and inescapably every summer, putting children in particular at risk. There was no prevention and no cure—no way of telling who would get it and who would be spared. Fearing that the virus spread through water, health officials closed down swimming pools and beaches. Children were told to rest and warned to stay out of crowds. Parents gave their kids a daily “polio test.” It became the crack in America’s middle-class picture window, leaving vivid reminders for all to see: wheelchairs, crutches, leg braces, iron lungs, and deformed limbs.

Ironically, the nation’s most famous polio survivor—Franklin Delano Roosevelt—had contracted the disease at age 39 in 1921. Polio, then called “infantile paralysis,” did not reach epidemic levels in the United States until the years following World War II. As president, Roosevelt had helped found the National Foundation for Infantile Paralysis, which would become the March of Dimes, a foundation devoted to helping rehabilitate polio survivors and supporting the quest for a vaccine. The organization revolutionized the way charities raised money, recruited volunteers, and penetrated the mysterious world of medical research.

Among the scientists it funded were the bitter laboratory rivals Albert Sabin at the University of Cincinnati and Jonas Salk at the University of Pittsburgh. Sabin championed a live-virus oral polio vaccine (the sugar-cube method) designed to trigger a natural infection strong enough to generate lasting antibodies against polio, yet too weak to cause a serious case of the disease. Salk favored a simpler killed-virus polio vaccine intended to produce antibodies (through injection) without creating a natural infection. Speed was on Salk’s side in the race.

Human testing in the 1950s was, by current standards, a primitive affair. There were few rules