https://pubmed.ncbi.nlm.nih.gov/35113901/ Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness Patients with vitamin D deficiency (<20 ng/mL) were 14 times more likely to have severe or critical disease than patients with 25(OH)D ≥40 ng/mL https://covid.us.org/2020/05/21/vitamin-d-versus-covid-19-part-one/ Vitamin D versus Covid-19: part one The study found that only 3.6% of persons with normal Vitamin D levels had severe or critical cases of Covid-19, whereas 79.2% of persons deficient in Vitamin D had severe or critical cases. < A 22 times higher risk of hospitalization if vitamin D deficiencies. You will need vitamin C and Zinc too, for it to work > https://www.mdpi.com/2072-6643/13/2/411 Vitamin D Supplementation to Prevent COVID-19 Infections and Deaths—Accumulating Evidence from Epidemiological and Intervention Studies Calls for Immediate Action A recent clinic-based cohort study among 185 patients diagnosed with and treated for COVID-19 at a University Hospital in Germany showed more than 80% lower risk of invasive mechanical ventilation or death (primary endpoint) and more than 90% lower mortality among patients with sufficient vitamin D levels compared with patients with vitamin D deficiency |