Greetings @tocho2, interesting your questions "how will we know that we have a good immune system?", in this regard there are clinical laboratory tests to measure the level of immunodeficiency, and then establish conditions to raise our defenses or at least reach a point of balance, generally our defenses are lowered by the high consumption of foods rich in acids (meat, sugar, milk among others), hence it is recommended to consume alkaline foods to balance our pH and improve our defenses.

In relation to your second question "How do we know if we are able to face an infection of this nature and come out victorious?", unfortunately science has little knowledge of the evolution and physiology of viruses, hence to date we have not been able to efficiently counteract viral attacks.

Thanks for your visit to the blog.