The objective of the study is to investigate the safety and potential efficacy of DAS181 for the treatment of severe COVID-19.

Each eligible subject is treated with DAS181 for 10 days and observed for 28 days from the first day of administration.

From day 1 to 10, once or twice a day, for 10 consecutive days, a total of 9 mg (7 ml) nebulized DAS181 is given. If DAS181 is given by twice a day, one vial containing 4.5 mg (3.5m1) DAS181 should be delivered with about 12-hour interval.

Key Inclusion Criteria:

1. Positive for RNA of SARS-CoV-2 from respiratory specimens or blood specimens
2. Hypoxemic
3. Severe COVID-19
4. If female, subject must not be pregnant or nursing.
5. Non-vasectomized males are required to practice effective birth control methods
6. Capable of understanding and complying with procedures as outlined in the protocol as judged by the Investigator and able to sign informed consent form prior to the initiation of any screening or study-specific procedures.

Exclusion Criteria:

1. ALT or AST> 8 x ULN
2. (ALT or AST> 3 x ULN) and (Total bilirubin> 2.5 x ULN or INR> 2.0 x ULN)
3. Female subjects who have a positive pregnancy test and are breastfeeding
4. Subjects using any other investigational antiviral drugs during the hospitalization before enrollment.
5. Subjects participating in other clinical trials
6. Subjects may be transferred to a non-participating hospital within 72 hours
7. People who cannot cooperate well due to mental illness, have no self-control, and cannot express clearly
8. Severe underlying diseases affecting survival
9. Critical COVID-19 requiring mechanical ventilator at the time enrolled