I used to swim in the Hudson too. Actually, the big problem in the late 40’s through the late 70’s was chemical dumping by a GE plant, maybe other businesses too. It’s true there at times is concern for sewage and other runoff.
I don’t agree with Carlin, I never agreed with this idea that we won’t get sick enough to build up immunity. I also don’t agree with being OCD about germs and using lots of antibacterial chemicals. I don’t use antibacterial soap, but I do wash my hands to wash away germs. I almost never use antibacterial wipes with chemicals, but I do use alcohol sometimes to clean my phone or wipe off something.
Children get exposed to germs no matter what unless they are in a bubble. Children also get vaccinated to teach their immune system to fight against certain diseases.
Getting chicken pox does not help you fight polio. Getting the Mumps does not help you fight measles. Getting a stomach virus does not help you fight Pertussis. This idea that getting sick helps you overall fight other specific diseases is not true as far as I know.
Getting a specific cold or flu will make you immune to that cold or flu. Ok, so do you want it when you’re ten years old or 40 years old? Better not to have it.
Diseases like Mumps, Chicken Pox, and some others are more dangerous in adulthood so people believe it best to get sick as a child, but that is different than exposing yourself to random unnecessary germs that can give you food poisoning or pneumonia.
Like everything, moderation is probably best.
Swimming in the Hudson and living in a dirty house is not going to protect you from covid.