RE: The people who live there have really powerful immune systems. They can drink the water there, but visitors should stick to bottled water.
The more the immune system is exposed to all sorts of germs, the more it can recognize invaders. However, this invader we face is NOVEL. Don’t know how the Indian immune system was able to react well to a NOVEL invader it just encountered.
There actually were a few corona viruses knocking around the world before COVID-19 showed up. They may have some sort of partial immunity.