Not trying to be flip, but why? "Natural" isn't always better, and as the obesity epidemic has shown, our evolutionary past hasn't done a perfect job of preparing us for our current environment.
You might be right, but I'm skeptical that there is any non-extreme limit to something as simple and mechanical as our innate immune system.
The innate response is less targeted, less effective, and causes potentially damaging effects like inflammation. The adaptive response is more targeted and more effective, with the tradeoff that it needs to be learnt.
I get sick after getting the flu vaccine and feel pretty bad for 1-3 days... then I get the flu anyway because they picked the wrong ones.
This looks like the inmune system is keep at the emergency level for 3 months.