The world has been dealing with this Corona virus since late December 2020, and China before that. Data on the severity of outcomes has been gathered from around the world, showing that severity is highly dependent on Vitamin D status. We in the US typically use the 25-OH-Vitamin D test to determine blood levels of vitamin D, with a test range of 10 ng/dl to 99 ng/dl (nanograms per deciliter), others use nmol/L (1 ng/dl = 2.5 nmol/L. Studies show that test results above 30 ng/dl (75 nmol/L) lead to minimal impact (sniffles?). In the Philippine study, at 30 ng/dl only 3.6% were in the severe and critical classifications, whereas at 20 ng/dl 40.3% were severe and 32.5% were critical. That is a massive difference – the difference between having a mild Cold or likely dying on a ventilator. If we were not seeing high death rates, we would be acting no differently than we did for the last 100 years, with everyone open for business. It looks like Vitamin D makes the difference.
A Philippine study 
With a deficient vitamin D status (<50 nmol/L) the probability of becoming Severe or Critical with COVID-19 was 72.8% against 7.2% with adequate vitamin D (>75 nmol/L). The Hazard Ratio is 10.0.
Consider this in your own life; I’ve kept my Vitamin D status above 70 ng/dl for the last 15 years; I’m 80, had maybe 6 colds in that time, and never had the Flu since reaching those levels! I take between 5000-10,000 IU in summer (sun shy – burn instantly) and 20,000 IU in winter. One more thing: if you carry much body fat, Vitamin D will sequester in your fat cells first, and not be available to your immune cells until they are full-up so-to-speak. If you go to integrated physician asking to raise your Vitamin D status in a hurry, they will probably give an injection of 50,000 to 100,000 IU to get that done in a hurry. You can do the same dose orally, and accomplish a similar result. Vitamin D toxicity, in one report I read, was achieved toward the end of the study period in a cohort dosed at 300,000 IU/day for a year; far above the scary limits you read in some health magazines.
I suggest my readers finish reading the rest of the Article Here to see the rest of the data – Very Convincing! The USA is now at (8/2020) 549 deaths per million Population – Ranked # 8 in the world, at about 1/2 of Belgium’s rate.
To Your Greater Health and Fitness, that we may do Good on Earth,
Frank Wilhelmi – Retired/consultant electronic engineer researches and reports practical strategies for optimizing health and fitness into advanced age. “I have a passion for living life to the fullest, and helping others to do the same.” A rapidly growing body of knowledge now enables us to extend our health and fitness decades beyond popular expectations.