inclusion criteria: older than 18 years old and younger than 75 years old for all study groups. meet the diagnostic criteria of covid-19 for different types (including ordinary type, heavy type and critical type) in infected patients. no medications or disorders that would affect vitamin d metabolism women must be on birth control and not pregnant ability and willingness to give informed consent and comply with protocol requirements

inclusion criteria: older than 18 years old and younger than 75 years old for all study groups. meet the diagnostic criteria of covid-19 for different types (including ordinary type, heavy type and critical type) in infected patients. no medications or disorders that would affect vitamin d metabolism women must be on birth control and not pregnant ability and willingness to give informed consent and comply with protocol requirements

inclusion criteria: 1. older than 18 years old and younger than 75 years old for all study groups. 2. meet the diagnostic criteria of covid-19 for different types (including ordinary type, heavy type and critical type) in infected patients. 3. no medications or disorders that would affect vitamin d metabolism 4. women must be on birth control and not pregnant 5. ability and willingness to give informed consent and comply with protocol requirements

inclusion criteria: 1. older than 18 years old and younger than 75 years old for all study groups. 2. meet the diagnostic criteria of covid-19 for different types (including ordinary type, heavy type and critical type) in infected patients. 3. no medications or disorders that would affect vitamin d metabolism 4. women must be on birth control and not pregnant 5. ability and willingness to give informed consent and comply with protocol requirements