“The hepatitis B vaccine has ... one of the most well-established safety records of any vaccine, and it’s one of our best. We’ve been using it for a long time. It’s one of our best tools to protect babies from chronic illness and liver cancer,” Sean O’Leary, chair of the Committee on Infectious Diseases for the American Academy of Pediatrics and an assistant professor of pediatrics at the University of Colorado School of Medicine, told CBS News. “This is a situation where one missed case is too many.”