Endogenous immunity due to selection has proven susceptible to break out biological threat events. and yet, that is how we adapt and adjust to the ever-changing biome.
pandemics prove this. the remaining members of the species are fitter, largely or wholly immune to the once-virulent pathogen.
vaccines abandon this sliding window of pathogenic fitness updates. in return they offer a house of cards scenario where multiple pathogen keys are able to attack multiple vector points simultaneously. all because selection is withheld for multiple pathogens across large populations.
hopefully natural selection and evolution are false models. if not, our species and some others we hide from selection processes with vaccines are due for a cumulative genetic update.