Vaccination stands as one of the most significant achievements in global health, saving an estimated 3.5–5 million lives annually. Thanks to vaccines, severe diseases like diphtheria, whooping cough, and polio, once common among UK children, are now rare. Historical data shows a sharp decline in disease cases after a vaccine is introduced, with some diseases, like smallpox, being completely eradicated. Had smallpox not been eliminated, it would have caused 5 million deaths worldwide each year!