inclusion criteria: - informed consent as documented by signature - hospitalized patient - ongoing covid-19 infection - vitamin d deficiency defined as a serum 25-hydroxyvitamin d concentration ≤ 50nmol/l( ≤20ng/ml) - > 18 years of age

inclusion criteria: - informed consent as documented by signature - hospitalized patient - ongoing covid-19 infection - vitamin d deficiency defined as a serum 25-hydroxyvitamin d concentration ≤ 50nmol/l( ≤20ng/ml) - > 18 years of age