What? A vaccine is nothing if an outside stressor on the immune system! It is designed to provoke the exact immune system response the real virus would, so it can react more quickly to future infections.
Unless you mean that the upper respiratory tract inflammation itself is what would cause the beneficial effect?
Yes, that's the common refrain - that the vaccine itself serves as that same stressor - and of course that is true, on the date that you take the vaccine.
But from then on, while you certainly maintain information from the vaccine in your immune system, you aren't ramping up the actual mechanisms of your immune system like you do when you actually experience influenza.
Think of the temperature raise, the white blood cell production, possible gastro-intestinal reactions - these are all bodily systems being ramped up to a level of performance they don't typically see.
My thought is that if I "successfully" avoid the flu for, say, the next 40 years, those bodily systems will not be as robust - even if I maintain the informational content of the vaccine itself.
Please, please, do not confuse this or lump this in with kooky anti-science, vaccine opponents. I'm just thinking out loud about how stressors on body systems work - which is what my parent was discussing.
Unless you mean that the upper respiratory tract inflammation itself is what would cause the beneficial effect?