To evaluate the efficacy and safety of azvudine in treatment of COVID-19

Inclusion Criteria:

1. age ≥18 years old, gender not limited;
2. Laboratory (RT-PCR) confirmed COVID-19;
3. the time from the first positive nucleic acid test to randomization does not exceed more than 4 days;
4. informed consent has been signed.

Exclusion Criteria:

1. known or suspected allergies to the components of azivudine tablets;
2. according to the latest version of the National Health and Medical Commission Diagnostic criteria of COVID-19, patients with severe novel coronavirus pneumonia was confirmed;
3. severe liver disease (TBIL>=2 times normal upper limit; ALTAST>=5 times normal upper limit);
4. subjects with severe renal insufficiency (glomerular filtration rate ≤60 mL/min/1.73 m2) or undergoing continuous renal replacement therapy, hemodialysis or peritoneal dialysis;
5. subjects with complication of malabsorption syndrome or any other condition affecting gastrointestinal absorption, requiring intravenous nutrition or not being able to take drugs orally;
6. subjectsis currently receiving anti-hiv treatment;
7. women who are breast-feeding during pregnancy or have a family plan during the trial period and within 6 months after the end of the trial;
8. participating in other clinical trials or using experimental drugs, except traditional Chinese medicine;
9. Other conditions that not appropriate to be enrolled into this study based on investigator's advise.