Vitamin D supplementation has already been shown to be beneficial in viral infections such as influenza and HIV. Patients with COVID 19 present with many symptoms, including fever, dry cough, sore throat, and nasal congestion, and bilateral lung glassy opacities in radiological findings. 

Vitamin D reduces the risk of microbial infection and death, including a physical barrier, cellular natural immunity, and adaptive immunity. It strengthens innate cellular immunity and acts party by introducing antimicrobial peptides, including the human cathelicidin LL-37 and by 1, 25-dihydroxyvitamin D and defensins. 

Vitamin D lowers the risk of microbial infection and death. It is a negative endocrine renin-angiotensin system (RAS) modulator. Vitamin D also increases the expression and concentration of ACE2, MasR and Ang-(1-7). It also has a potential protective role against acute lung injury or acute respiratory distress syndrome. 

Vitamin D favors the ability of macrophages to mature and prevents macrophages from releasing too many inflammatory cytokines and chemokines. Additionally, Vitamin D supplementation has a favorable effect on many viral infections. 

Resources: Murdaca G, Pioggia G, Negrini S. Clinical and Molecular Allergy. 2020; 18: Article number 23.