Immunity Is Cultivated: Minor Illnesses Are the Body's Make-Up Classes (Steady-State Structure x Training Function Coupling Hypothesis)

Why do some people catch minor illnesses all year round yet rarely get seriously ill, while others never get sick and then collapse from one major illness? This paper proposes: the immune system is a coupled system of steady-state structure and training function. Illness, vaccination, and treatment are three modes of this coupling. It recombines four established discoveries (immunological memory, trained immunity, the hygiene hypothesis, original antigenic sin) into one framework, and derives three falsifiable predictions.