All vaccine components undergo a process rendering them incapable of causing a disease. The components that protects against Polio (infantile paralysis) undergo a process to neutralize the active virus.
The components that protect against tetanus and diphtheria are proteins secreted by bacteria (causing symptoms to appear, (toxins)), which undergo decontamination and weakening. This enables the body to protect itself against diseases, even though those proteins are no longer toxic.
The mechanism known as innate or natural immunization is passed down from parents to offspring in the mother’s womb itself and varies from species to species. The human body has an inbuilt defense system to counter many health related issues and problems, while some other diseases are countered by giving vaccination to the children after their birth. We use a kids favourite kid's toys or books or talk about something else to take their mind off the injection, so that kids take vaccination happily without getting scared.