There are many cases that come to mind where someone has not been exposed to a potential allergen (growing up being sheltered from it, childhood aversion to it

There are many cases that come to mind where someone has not been exposed to a potential allergen (growing up being sheltered from it, childhood aversion to it that was never reassessed in adulthood, simple lack of that allergen in previous environments) and I think it’s fair to want to avoid someone suddenly having new allergic reactions, especially when those reactions can “suck”.