[Dylan16807]

> it's either working properly, or it's not

It can be normal, over-active, under-active, and likely both. "working or not" is too simplistic for this discussion.

> A 'boosted' / over-active immune system results in auto-immune diseases like Crohn's (which is what I have).

Yes, but that doesn't mean that a temporary boost couldn't potentially help in certain situations.

Along those lines, I bet if you really needed a specific live vaccine your doctor would have you suspend that drug for a little bit.