Dr. Peter Salk still remembers the day his father learned the American manufacturers of the revolutionary polio vaccine he developed had messed up a batch — with deadly consequences. “This was probably one of the worst moments of his life, when this happened,” said Salk. “He had full confidence in the safety of the vaccine — if manufactured correctly. And this just was a devastating experience.” Salk’s father was Dr. Jonas Salk, the American virologist whose development of a crucial polio vaccine in 1955 is widely credited with finally reining in the devastating spread of polio. While the vaccine itself was safe, failure by the infamous (and defunct) Cutter Laboratories south of the border to manufacture it properly led to thousands of American children who got the vaccine being infected instead.