All vaccination does is replace acute illness with chronic disease. Naturally reared, well-bred animals can encounter illness and either develop immunity without getting sick, as mine do, or they can suffer a brief acute illness and then develop immunity. Encounters with illnesses are good for animals. If an animal literally succumbs to every pathogen it encounters, it's either being raised abysmally or it's genetically very unhealthy. Vaccines cause more problems than they prevent, but the fact is that most pets in this country are not healthy enough to fight off disease anymore.
Vaccines do nothing but prevent the body from expressing a normal immune response to acute illness.
They don't build health, they don't increase the strength or vigor of the immune system. You will never really break free of the cycle unless you stop vaccinating, scary as that is. This is especially true for those of us who are breeders. You can also draw your own parallel and apply this to individual animals - dogs, cats, others. I don't believe that veterinarians in general over-vaccinate for pecuniary motives.