When you're young you have your best chance by far against most diseases, and after you've had it you likely pick up some degree of immunity to it (and other th

When you're young you have your best chance by far against most diseases, and after you've had it you likely pick up some degree of immunity to it (and other things like it) that you carry with you when you become a parent, or a grandparent. One of the signs of age is how rarely you catch flus. All those mutations recycle and even though you've become weak, you've built up a library. Not all diseases behave like that, and all should be treated differently. Really you should just do public health, and have statistics, and let those make the decisions instead of doing policy by omission, or deciding by intuition.