In the general linear model adjusted for age, sex, comorbidities, and BMI, serum 25(OH)D concentrations were significantly lower among COVID-19 patients than the 2018–2019 controls [ln transformed values of 3.32 ± 0.04 vs. 3.46 ± 0.022 ln (nmol/L), P = 0.014]. Multivariable logistic regression showed that male sex (OR: 2.26; 95% CI: 1.06, 4.82), advanced age (≥65 y) (OR: 4.93; 95% CI: 1.44, 16.9), and vitamin D deficiency (<30 nmol/L) (OR: 2.72; 95% CI: 1.23, 6.01) were significantly associated with COVID-19 severity (all P < 0.05).
These findings suggested that vitamin D deficiency impacts COVID-19 hospitalization and severity in the Chinese population.
Vitamin D Deficiency Is Inversely Associated with COVID-19 Incidence and Disease Severity in Chinese People — The Journal of Nutrition, Volume 151, Issue 1, January 2021, Pages 98–103, https://doi.org/10.1093/jn/nxaa332
More links are in my last post Vitamin D – What’s Your Level?
I am hoping all of my Chinese relatives read this.
lifeunderwriter.net 
I would think this could be extrapolated to other nationalities as well. I know I’m watching my vitamin D level even more carefully now. Last time it was 60.
Your D level is awesome probably the result of supplements and living large in the Sunshine State. I also agree with your extrapolation comment.
Yes, 2000 IU D3 a day since 1992 when my level was first checked and found to be 16.