My friend’s husband, Indian, NEVER gets sick. He is nearly 72 and he can’t remember the last time he even got a cold. My friend, his wife, has had covid, colds, flus, and everything else but he never gets it. I would imagine the Indian immune system is pretty robust after growing up in such a dirty place.
There are several spices used in Indian food that are great for boosting immunity and fighting off illness. Turmeric is one of them. There are other ones bit thats the first one that comes to mind. I take it every day. Also add it into my chili.
Maybe it’s the vitamin D3 and zinc cocktail that I’ve been taking for years. I added Quercitin when Covid came along.
I wonder if your friend’s husband had been given significant amounts of anti malarial medication during his youth which built up defenses against viruses and germs, or which left him with lifelong immunity because of all the dead pathogens in his system.
Flies don’t get sick.