Immunization is the process of making your child resistant to certain infectious diseases by administering a vaccine by either injection, ingestion or inhalation. The vaccine contains killed or weakened microbes of a disease or part of the microbe, such as the DNA that do not cause the disease but stimulate the immune system as if it were under attack. This helps the immune system in protecting the body against future attacks of the actual microbe. Different vaccinations are recommended for different age groups.