Evaluation of the Efficacy and Safety of Nano-S1

Inclusion Criteria: 1. Participants are hospitalized in a COVID unity or outpatient follow-up by the investigator 2. Participants who have positive SARS-CoV-2 test result and the onset of symptoms of COVID-19 ≤7 days prior to randomization, Not exceed the 7th day since the beginning of disease symptoms; and the randomization's day. 3. Present at least one of these symptoms: Participants who have one or more mild or moderate COVID-19 symptoms: Fever, general signs such as: headaches, asthenia, myalgia, arthralgia, etc... ENT signs such as: Sore throat, anosmia, agueusia, hypoacusis, deafness, etc... Digestive signs such as: diarrhea, vomiting, abdominal pain, etc... Respiratory signs such as: dyspnea, cough, etc... And cutaneous signs such as: skin rash, livedo, etc... 4. Present an oxygen saturation patients with SpO2 \> 94% at room air 5. Present at least one of these risk factors: Participants who satisfy one or more than one of the following high risks for progression to severe COVID-19, including death: Age 65 years old Or -Age between 18 and 64 years old with at least one of these risk factors: Obesity (BMI\> 30 kg/m2),and/or diabetes under treatment and/or cardiovascular disease (including hypertension and stable angina) high blood pressure and/or Chronic obstructive pulmonary disease (COPD) disease and/or asthma and/or Neoplasia (solid tumour; hematological malignancy) neoplasia, and/or a blood disease and/or heart failure and/or chronic renal failure (Cl creat\> 30Mml/min) and/or unstabe angina and/or autoimmune disease. 6. Have signed the informed consent to participate in this trial. Exclusion Criteria: * Non observance.Non-compliant patient With drawal of Consent. Patient who refuses blood samples.