The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality

The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality: Vitamin D levels are severely low in the aging population especially in Spain, Italy and Switzerland. This is also the most vulnerable group of the population in relation to COVID-19. It should be advisable to perform dedicated studies about vitamin D levels in COVID-19 patients with different degrees of disease severity.