Let’s face it: the only real justification for using vaccines to “immunize” ourselves against disease is derived from the natural fact that when challenged by infectious agents the humoral arm of our immune system launches a successful response capable of conferring lasting immunity. Were it not for the elegance, proficiency, and mostly asymptomatic success of our recombinatorial immune system in dealing so well with infectious challenges, vaccination would have no cause, no scientific explanation, no justification whatsoever.
In fact, ever since the adaptive, antigen-specific immune system evolved in early vertebrates 500 million years ago, our bodies have been doing a pretty good job of keeping us alive on this planet without need for synthetic, vaccine-mediated immunity. Indeed, infectious challenges are necessary for the development of a healthy immune system and in order to prevent autoimmune conditions from emerging as a result of TH2 dominance. In other words, take away these natural infectious challenges, and the immune system can and will turn upon itself; take way these infectious challenges and lasting immunity against tens, if not hundreds of thousands of pathogens we are exposed to throughout our lives, would not be possible.