Immunization is a modern miracle; it has saved millions of lives worldwide and its origin dates back ancient Greece. In the 14th century the Chinese discovered and used a primitive form of vaccination called variolation. The aim was to prevent small pox by exposing healthy people to tissue from the scabs caused by the disease this is the first recorded attempt at vaccination. The British physician Dr. Edward Jenner in 1796 discovered vaccination in its modern form and proved to the scientific community that it worked. He was considered the founder of vaccinology in the west after he inoculated a 13year old boy with vaccine of a virus (cow pox) and demonstrated immunity to small pox. By 1798, the first small pox vaccine was developed. Immunization is the most effective method of preventing infectious diseases. Widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the restrictions of disease such as polio, measles and tetanus. Generally immunization involves stimulating immune responses with infectious agents, i.e. priming the immune system with an immunogen with the intention of creating specific resistance to an infectious disease. Simply put a process by which an individual’s immune system becomes fortified against an agent.