Inclusion Criteria:  males and females aged 18 to 75 years who did not take Vitamin D supplementation COVID-19 clinical features signed informed consent to participate in the research.  Exclusion Criteria:  pregnancy or nursing primary hyperparathyroidism or hypercalcemia other etiologies (including 24-hydroxylase mutation) a history of granulomatous diseases severe gastrointestinal diseases (clinically apparent malabsorption syndrome) liver disease kidney disease individual intolerance drug vitamin D supplementation in a dose of more than 800 IU per drugs known to affect vitamin D metabolism (e.g., anticonvulsants, glucocorticoids, diuretics) alcohol and drug addiction. history of cancer (less than 5 years)