Why aren't the Amish being heavily affected?
https://www.nobelprize.org/prizes/medicine/1913/richet/lecture/
"(1) a subject that had a previous injection is far more sensitive than a new subject; (2) that the symptoms characteristic of the second injection, namely swift and total depression of the nervous system, do not in any way resemble the symptoms characterizing the first injection; (3) a three or four week period must elapse before the anaphylactic state results. This is the period of incubation."