This is based on nothing but conjecture, but to me it seems likely that risks are mostly cumulative. Now it's true that the body can repair itself but that is not true in all cases. Gato, Berenson perhaps others report that heart and neurological (nerve) disorders seem to be increasing (presumably) driven by the vaxxes. Alas, nerve and heart tissue do not regenerate (as a rule? exceptions?) Maybe the immune system fades with repeated boosts; I already "lost" this argument on another forum, because I could cite no evidence.