Typically, vaccine development is based on this successful experiment of nature. An iterative approach of fundamental research coupled with empirical testing of immunogens leads to the identification of a product that, when given in an appropriate formulation and dose before exposure, induces immune responses that mimic the response to natural
infection and protect recipients from the development of clinically apparent disease when they are exposed to the virus. Historically, the development of vaccines has relied heavily and successfully on empirical testing