This is a prospective, multicenter, randomized, controlled, superiority clinical trial. It is expected that the test group would have better effectiveness than the control group in the primary evaluation indicator (time to negative viral nucleic acid detection from the start of study treatment). The test group will use the investigational medical device Hydrogen-Oxygen Generator with Nebulizer (Shanghai Asclepius Meditec Co., Ltd.) + basic treatment (the investigator provides corresponding symptomatic support treatment based on the condition of the patients), and the control group will use the hospital routine oxygen supply equipment (wall oxygen or cylinder oxygen) + basic treatment, to evaluate the effectiveness and safety of the investigational medical device Hydrogen-Oxygen Generator with Nebulizer for adjuvant treatment of COVID-19 patients.

A total of 188 subjects who met the requirements of this study will be randomized into the test group or the control group in a 1:1 ratio to receive treatment, and the subjects will be observed and evaluated in the period from treatment after enrollment to discharge.

All enrolled subjects will receive treatment and visit, including screening visit (within 3 days before enrollment), randomization and treatment visit (Day 0), 1, 2, 3, 5, 7, 10, and discharge visit after treatment.

The primary effectiveness evaluation indicator (time to negative viral nucleic acid detection from the start of the study treatment), the secondary effectiveness evaluation indicators (viral nucleic acid negative conversion rate, imaging evaluation, inflammatory indicators such as CRP, IL-6, lymphocytes, clinical response rate at 7 days of treatment, recovery rate and recovery time of major symptoms, index oxygen saturation, and Ct value of nucleic acid detection), and safety evaluation indicators ( incidence of AE and SAE, incidence of device deficiencies) of the two groups will be collected and analyzed.

Inclusion Criteria:

• Male and female subjects aged between 18 and 80 years old (inclusive).
• Diagnosed as general type of COVID-19 according to the criteria of Scheme for Diagnosis and Treatment of 2019 Novel Coronavirus Pneumonia (Trial Version 9).
• Subjects who are willing to participate and provided written informed consent form.

Exclusion Criteria:

• Diagnosed as mild, severe, critical or asymptomatic type of COVID-19.
• Subjects in the treatment or active stage of malignant tumor.
• Subjects who are intolerable to inhalation treatment.
• Subjects with mental disorders or cognitive impairment who are unable to provide consent.
• Subjects with any immunodeficiency requiring chronic treatment with any corticosteroid or other immunosuppressants.
• Complicate serious primary diseases such as heart, liver, kidney, and hematopoietic diseases; acute exacerbation phase of chronic obstructive pulmonary disease, or acute attack of bronchial asthma.
• Subjects who are using any non-expectorant antioxidant drug, including large doses of vitamin C and vitamin E.
• Subjects who are participating any other clinical study of any investigational drug or medical device.
• Pregnant or lactating women.
• Any other condition judged as inappropriate to participate in this study by the investigator.