Pertussis vaccine example
In the mid-1970s in England and Wales, anti-immunization groups caused parents to question the value of pertussis vaccine. As a result, immunization rates fell from 81 to 31% in a span of just a few years. Two epidemics of pertussis (whooping cough) followed, and many children died needlessly. As the population was confronted with the scourge of pertussis returning to their community, immunization coverage rose steadily and even surpassed previous highs.