Having been around the Mennonite folks....there’s this other little aspect of their life...they work outdoors a great deal and collect a ton of vitamin D. If you went and measured up a community of Amish/Mennonite folks...they’d all be mostly at the top level. I think the science community is missing this angle of the story.
Vitamin D for COVID-19: real-time meta analysis of 142 studies
https://vdmeta.com/
Unfortunate choice of a URL, but good info.