The practice of immunisation dates back hundreds of years. Buddhist monks drank snake venom to confer immunity to snake bite and variolation (smearing of a skin tear with cowpox to confer immunity to smallpox) was practiced in 17th century China. Edward Jenner is considered the founder of vaccinology in the West in 1796, after he inoculated a 13 year-old-boy with vaccinia virus (cowpox), and demonstrated immunity to smallpox.
There are many approaches to vaccine development, but vaccines can be broadly classified by how the antigen(s), the active component(s) that generate a specific immune response against the disease-causing organism, are prepared.
Vaccine manufacture and composition is complex and tightly regulated to maximise potency and safety. The safety of the individual components, and of the vaccine itself, in the amounts administered, must be demonstrated before a vaccine can be approved for use in New Zealand.