Vitamin D – contrary to vitamin K – does not associate with clinical outcome in hospitalized COVID-19 patients

SARS-CoV-2 causes remarkably variable disease from asymptomatic individuals to respiratory insufficiency and coagulopathy. Vitamin K deficiency was recently found to associate with clinical outcome in a cohort of COVID-19 patients. Vitamin D has been hypothesized to reduce disease susceptibility by modulating inflammation, yet little is known about its role in disease severity. Considering the critical interaction between vitamin K and vitamin D in calcium and elastic fiber metabolism, we determined vitamin D status in the same cohort of 135 hospitalized COVID-19 patients by measuring blood 25(OH)D levels. We found no difference in vitamin D status between those with good and poor outcome (defined as intubation and/or death). Instead, we found vitamin D sufficient persons (25(OH)D >50 nmol/L) had accelerated elastic fiber degradation compared to those with mild deficiency (25(OH)D 25-50 nmol/L). Based on these findings, we hypothesize that vitamin D might have both favorable anti-inflammatory and unfavorable pro-calcification effects during COVID-19 and that vitamin K might compensate for the latter.