O educated doctor, who went to […] school, I’m glad you’ve written this, but I think in the rich and interesting sentence “Your immune system is the ONLY 100% full-proof thing we have to fight against this.” you meant ‹foolproof›. Also, to get rid of an unwanted steering element in the sentence, ‹possess› ought to be substituted for ‹have›. I am a doctor of words!