But I also have to wonder if the kids with auto-immune diseases or "common" allergies elsewhere might just die the first time they encounter some event that'd otherwise be caught and treated in "the first world" ?

> The hygiene hypothesis has difficulty explaining why allergic diseases also occur in less affluent regions. Additionally, exposure to some microbial species actually increases future susceptibility to disease instead, as in the case of infection with rhinovirus (the main source of the common cold) which increases the risk of asthma

I think having a common cold infection each year does not bring any benefits, it certainly does not make anybody immune to common cold

Plus the air is not always “fresh” depending on where you live and what time of year. Ozone, smog, smoke, etc.

Plus for those of us with allergies, an open window during for example ragweed season can be a nightmare.

https://rachel.fast.ai/posts/2024-08-13-crowds-vs-friends/

"Your Immune System is Not a Muscle"

> Four main categories of pathogens that humans deal with are viruses, bacteria, fungi, and parasites. The evidence for pathogens that may be beneficial to the immune system is almost entirely for parasitic worms and friendly (commensal) bacteria. In contrast, many viruses can even trigger the onset of autoimmune diseases or allergies.

Putting people in a small poorly-ventilated box with a bunch of strangers (some of whom perhaps recently flew to the other side of the planet and back) is the abberant behavior, really.