I agree we all are different and this one size fits all model will change, it’s happening now as science discovers what is an immune system and how it really works. The more I study vaccines I’m learning the science is based on fraud and deceit...vaccines will eventually be viewed the same way we view the kind of medical practices that spouted bleeding a person reduced the humors was a way of curing disease.
Medical historians will view allopathic medicine as a horror story neve to be repeated or forgotten the war on disease and who cares about the patient will be shelved as a bad part of human history.
https://en.m.wikipedia.org/wiki/Bloodletting
Thank you @vickybantin
Genetic mutations make kids more susceptible to illness.
MTHFR Gene mutation is an example and there are many others.