Inclusion Criteria:  all patients with COVID-19 admitted to the ICU with vitamin D deficiency [25-hydroxyvitamin D (25(OH)D) ≤ 30 ng/ml]  Exclusion Criteria:  less than 24 hours in ICU by any reason chronic decompensated disease with extrapulmonary organ dysfunction (tumour progression, liver cirrhosis, congestive heart failure) with a life expectancy of less than 48 hours atonic coma allergic reaction on cholecalciferol or herbal oil