The hypothesis, as it now stands, contends that children in developed countries no longer run the gauntlet of infectious diseases that they used to, and so grow up with inexperienced, jumpy immune systems.21 They are healthier in the short term, but they launch panicked immune responses to harmless triggers, like pollen. This concept delineated an unenviable trade-off between infectious and allergic disease, as if we were destined to suffer one or the other.
