Vitamin D Determines Severity in COVID-19: Researchers Urge Government to Change Advice - scitechdaily.com/vitamin-d-dete…
The authors of the article, just published in the Irish Medical Journal, analyzed all European adult population studies, completed since 1999, which measured vitamin D and compared vitamin D and death rates from COVID-19.
vitamin D can also support the immune system through a number of immune pathways involved in fighting SARS-CoV-2. Many recent studies confirm the pivotal role of vitamin D in viral infections.
This study shows counter intuitively, countries at lower latitude and typically sunny countries, such as Spain and Northern Italy, had low concentrations of vitamin D and high rates of vitamin D deficiency. These countries also experienced highest infection death rates in Europe.
The northern latitude countries of Norway, Finland, and Sweden, have higher vitamin D levels despite less UVB sunlight exposure, because supplementation and fortification of foods is more common. These Nordic countries have lower COVID-19 infection and death rates.
The correlation between low vitamin D levels and death from COVID-19 is statistically significant.
Here are some medical research studies on Vitamin D deficiency & its link to mortality rate with COVID-19. Vitamin D is critical for strong immune system & most of us are deficient in it these days. 
