On April 26, 1954, Janice Nichols rolled up her sleeve and became part of the largest vaccine trial in history. That year, 1.8 million first to third graders were vaccinated for polio across 44 U.S. states, Canada and Finland. At the time she entered the research study, Nichols was 6 years old. She had already survived polio herself, and was grieving the death of her twin brother, who had died just days before she contracted the disease in 1953. She and thousands of children like her would come to be known as Polio Pioneers — children who did what they could to help find a solution to this public health menace. Research shows that confidence in vaccine effectiveness is slipping , despite decades of clear evidence to the contrary. This shift has occurred in part because the stories that once served to build public trust are no longer being heard.…