This is an interesting video from 7 months ago. It details how Vit-D activates immunity, including an antiviral protein we produce. (Cathelicidin) Talks about how the nasal mucosa have an enzyme to activte, then use, Vitamin D. How it acts as an inhibitor of pro-inflammatory cytokines and inhibits the cytotoxic effects of T cells and B cells. (Slide at 8 min) Like maybe that young Chinese M.D. who first called out Covid-19 then died of it might have had a better chance had he not been indoors treating patients all the time, then tossed into a Chinese dungeon for interrogation… /snark; it also helps with allergies.
I think this goes a long way toward explaining the cyclical mature of Influenza and “winter colds”. His chart of vit-D levels by region, with the middle east low, might also help to explain the degree of outbreak in Iran. Covered head to toe in cloth year round, and indoors, now, to great extent. So a low vit-D level and lowered immunity. Below 20 ng/ml is very deficient, and the Middle East has 90% of their population below that level. (Slide at 9 min.) Then a bit of a hoot when Australian dematologists are at 83%. Sunscreen much? (Slide 10:40) At 12 minutes walks through a series of papers / references. I was especially interested in the slide at 20 minutes showing IL-5 cytokine down modulated from about 550 pg/ml to just under 100 pg/ml, and “essentially non-allergic”. The airway contriction vs. not constricted IMHO has significance for Covid-19 treatement.
So get some sun, or supplement your Vit-D. If a family member is stuck in a “facility”, get their level checked.
UPDATE: It looks to me like China, especislly in the north, north Iran, and Europe are short of UV. Especially in the smoggy industrial areas of China. So likely also vitamine D depleted.
Prior Vit-D article: https://chiefio.wordpress.com/2020/03/01/get-sun-take-vit-d/