The Winter v Summer part is the easiest part. Vitamin D levels are at their lowest in the Winter, so if one thinks of Vitamin D as being an essential hormone (it's not really a "Vitamin") that assists in driving essential human health, there is your answer for that part of your question.

As for "ignoring immunity protocols" I am not stating or advocating that, and quite the opposite. I am also not saying disease does not exist. Again, quite the opposite.

Taking C, D, Iodine, K2, Selenium, Zinc, etc. and even going as far as to take "trace minerals", Copper, Silver, etc. is all within bounds (and look to others who have done more experimentation with that second list than I to know how much to take). Other things like Quercetin, etc. are also great because they accelerate some of the Vitamins/Hormones in the first list. Indeed, one could say the same thing about Zinc, really. Sort of. Anyway, moving on: now we get to the biotics part. We are the only organism in the USA that doesn't have a de-bugging protocol. So... that's crazy. It's my view that a lot of our diseases are actually caused by biotics that enter us and live inside us and wait for their moment (when you are weak enough, etc.) to start causing mayhem (Lyme Disease, Psoriasis, Cancer, etc.). This is exactly why those vitamins and hormones are so important. But you can go the next step and take things like Ivermectin, Fenbendazole/Albendazole, etc. to attack these worms/bugs and do really well with them.

As for "all of the children getting sick from a party", that's probably multifactor, but indeed someone could possibly communicate a bug from their body to yours. We all on this thread right now have all of the ingredients we need to get really, really sick. And perhaps even to get cancer, etc. How those elements in our body express is down to factors like your vitamin and hormone levels, blood sugar levels, etc.