COVID-19(8) serum(8) Vitamin D(8) Inflammatory(8) SARS-CoV-2(8) Patient(8) risk(8) Vitamin(7) Cohort(7) Hospitalization(7) with COVID-19(7) Mortality(7) COVID-19 patient(5) tested(4) oxygen(4) Level(4) Deterioration(4) mortality rate(4) primary endpoint(4) primary endpoints(4) SARS-CoV-2 test(4) likelihood(4) therapy(4) reducing(4) Cytokine release syndrome(4) need for oxygen(4) pro-inflammatory cytokines(4) disease(4) inflammatory.(4) oxygen support(4)