BACKGROUND Vitamin D population status may have possible unappreciated consequences to the coronavirus disease 2019 (COVID-19) pandemic. Α significant association between vitamin D sufficiency and reduction in clinical severity and inpatient mortality from COVID-19 disease has recently been shown, while a recent study has claimed lower COVID-19 cases in European countries with a better vitamin D status. Low serum 25-hydroxyvitamin-D [25(OH)D] was identified as an independent risk factor for COVID-19 infection and hospitalization, and administration of 0.532 mg (21280 IU) of calcifediol or 25(OH)D, followed by 0.266 mg on days 3 and 7 and then weekly until discharge or intensive care unit admission significantly reduced the need for intensive care unit treatment. AIM To elucidate the role of vitamin D European population status in the COVID-19 pandemic, data from the Worldometer were analyzed. METHODS Linear regression explored the correlation between published representative-standardized population vitamin D concentrations and the number of total cases/million (M), recovered/M, deaths/M and serious-critically ill/M from COVID-19 for 26 European countries populated > 4 M (Worldometer). Life expectancy was analyzed with semi-parametric regression. Weighted analysis of variance/analysis of covariance evaluated serious-critical/M and deaths/M by the vitamin D population status: Deficient < 50, insufficient: 50-62.5, mildly insufficient > 62.5-75 and s ufficient > 75 nmol/L, while controlling for life expectancy for deaths/M. Statistical analyses were performed in XLSTAT LIFE SCIENCE and R (SemiPar Library). RESULTS Linear regression found no correlation between population vitamin D concentrations and the total cases-recovered/M, but negative correlations predicting a reduction of 47%-64%-80% in serious-critical illnesses/M and of 61%-82%-102.4% in deaths/M further enhanced when adapting for life expectancy by 133-177-221% if 25(OH)D concentrations reach 100-125-150 nmol/L, sustained on August 15, 2020, indicating a truthful association. Weighted analysis of variance was performed to evaluate serious-critical/M ( r 2 = 0.22) by the vitamin D population status and analysis of covariance the deaths/M ( r 2 = 0.629) controlling for life expectancy ( r 2 = 0.47). Serious-critical showed a decreasing trend ( P < 0.001) from population status deficient ( P < 0.001) to insufficient by 9.2% ( P < 0.001), to mildly insufficient by 47.6% ( P < 0.044) and to sufficient by 100% (reference, P < 0.001). For deaths/M the respective decreasing trend ( P < 0.001) was 62.9% from deficient ( P < 0....

Background: Vitamin-D population status may have possible unappreciated consequences to the COVID-19 pandemic. Α significant association between vitamin-D sufficiency and reduction in clinical severity and inpatient mortality from COVID-19 disease was recently shown while a recent study has claimed lower COVID-19 cases in European countries with a better vitamin D status. Aims: To further elucidate the possible role of vitamin D population status in the COVID-19 pandemic, we examined the associations between published representative and standardized population vitamin D data on European population vitamin D status and the Worldometer COVID-19 data. Methods: Data from the Worldometer on 26 European countries populated &gt;4 million (M) were analyzed. Results: On 19-June-2020, linear regression found no correlation between published representative-standardized population vitamin-D concentrations and the total cases-recovered/M, but negative correlations predicting a reduction of 47-64-80% in serious-critical illnesses/M and of 61-82-102.4% in deaths/M, further enhanced when adapting for life expectancy by 133-177-221% if 25(OH)D concentrations reach 100-125-150 nmol/L. On 15-August-2020 these correlations were sustained indicating a truthful association, yet not proving causality. Weighted ANOVA was performed to evaluate serious-critical/M (R2=0.22) by the vitamin-D population status (deficient-D &lt;50, insufficient-IN 50–62.5, mildly insufficient-MIN &gt;62.5–75 and sufficient-S &gt;75 nmol/L) and ANCOVA the deaths/M (R2=0.629) after controlling for life expectancy (R2=0.47). Serious-critical showed a decreasing trend (p&lt;0.001) from population status D (p&lt;0.001) to IN: 9.2%, p&lt;0.001, MIN: 47.6%, p&lt;0.044 and S: 100% (reference). For deaths/M the respective decreasing trend (p&lt;0.001) was 62.9% from D (p&lt;0.001) to IN (p&lt;0.001), 65.15% to MIN (p&lt;0.001) and 78.8% to S (p=0.041). Conclusions: Following the Endocrine Society’s expert committee recommendations, without previous testing being necessary, reaching and maintaining a serum 25(OH)D of 100–150 nmol/L (40–60 ng/ml) could be achieved by an initial supplementation with the upper tolerable daily intake doses (IU/day) for up to two months: &lt;1yr 2000, 1-18yrs 4000 and all adults 10,000 (obese x 2–3 times more) and then with the maintenance proposed doses that do not require medical supervision, practically identical with the IOM’s upper tolerable limits: 1000 &lt;6m, 1500 6m-1yr, 2500 1-3yrs, 3000 4-8yrs, and 4000 &gt;8yrs, with adults and adolescents requiring 4000–5000 (obese x 2). Vitamin D may not prevent SARS-CoV-2 from spreading but may protect, without any risk of toxicity, from serious-critical illness and death from COVID-19 disease. While awaiting well-designed prospective studies, following the proposed approach, the gain for global public health and not only against SARS-CoV-2 may just prove invaluable.