This is a randomized, open label study to evaluate the efficacy and safety of calcitriol supplementation in COVID-19 patients with vitamin D deficiency.

This is a randomized, open label study to evaluate the efficacy （clinical and laboratory change）and safety （serum calcium） of calcitriol supplementation in COVID-19 patients with vitamin D deficiency.

Inclusion Criteria:

1. Hospitalized symptomatic COVID-19 patients;
2. COVID-19 nucleic acid Ct value < 28 (both orf1ab gene Ct value and N gene Ct value < 28);
3. Vitamin D deficiency: 25OHD ≤ 20ng/ml;
4. Age: 18-70 years old;

Exclusion Criteria:

1. Asymptomatic COVID-19 patients ；
2. Hypercalcemia;
3. History of primary hyperparathyroidism;
4. History of triple hyperparathyroidism;
5. Patients who are allergic to calcitriol;
6. Pregnant or lactating women;
7. Patients with severe heart or lung diseases or tumor history;
8. Patients already taking vitamin D or its similar preparations;
9. Participants in other interventional clinical studies (including taking paxlovid);
10. Patients with renal insufficiency (eGFR<60ml/min/1.73m2);
11. Patients considered unsuitable for this study by the investigator；