The aim of this study is to evaluate the effectiveness and safety of MIR 19 ® in preventing development of moderate and/or severe course of the disease in mild COVID-19 outpatients.

Primary endpoint:

The proportion of patients with the development of moderate or severe COVID-19 disease (in accordance with the criteria specified in the Interim Guidelines "Prevention, diagnosis and treatment of new coronavirus infection (COVID-19)" by the Ministry of Health of the Russian Federation, version 14 of 27.12.2021 or current at the time of the study) by the 28th day of observation.

This is Phase 2b-3 multi-center controlled randomized study to assess the efficacy and safety of MIR 19 ® via 7 days treatment in a dose of 5.55 mg/day of participants with symptomatic mild COVID-19 who did not require hospitalisation.

The MIR 19® is a complex of siRNA, targeting Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) RNA-dependent RNA polymerase (RdRp) and peptide dendrimer (KK-46).

This study involved 2 cohorts who received:

1. 5.5 mg of the MIR 19 ® per day via inhalation route plus standard therapy which included symptomatic treatment, without any etiotropic drugs.
2. Standard therapy which included symptomatic treatment as well as etiotropic drugs except MIR 19 ®.

All subjects will undergo scheduled safety and efficacy assessments as outpatients to the end of the follow-up period.

Inclusion Criteria:

• Men and women over the age of 18 who have been diagnosed with COVID-19 and who need therapy on an outpatient basis according to the Interim Guidelines "Prevention, diagnosis and treatment of new coronavirus infection (COVID-19)"by Ministry of Health of the Russian Federation. Version 14 from 12/27/2021.
• Able to give informed consent and attend all study visits
• Duration of the disease from the first symptoms (presence of at least one of the following symptoms: fever, cough, myalgia, weakness, shortness of breath, headache, nausea, stool disorders, loss of appetite) up to the day of screening no more than 5 days.
• Negative pregnancy test for women with preserved reproductive potential
• Participants must agree to use the reliable contraception while on study medication and for posttrial contraception for 3 month
• The patient's ability to inhale the experimental drug

Exclusion Criteria:

• Respiratory rate is more than 22 / min
• Oxygen saturation - SpO2 ≤ 94%.
• Decreased level of consciousness, agitation.
• Unstable hemodynamics (systolic blood pressure less than 100 mmHg or diastolic blood pressure less than 60 mmHg).
• Long-term systemic corticosteroid exposure.
• Autoimmune or inflammatory diseases (systemic / localized), as well as oncological diseases.
• Symptoms of moderate, severe or critical COVID-19 at the time of screening
• Positive blood tests for HIV, hepatitis B and С, syphilis.
• Pregnancy and breast-feeding.
• Previous adverse reactions to the active substance and/or excipients included in the drug
• Chronic diseases of the cardiovascular system
• Type 1 diabetes.
• The following laboratory parameters are excluded: Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, total and direct bilirubin >4 x upper limit of normal (ULN);
• C-reactive protein (CRP) level > 10 mg/L.
• Participation in other investigational drug or device clinical trials within 90 days prior to screening.
• History of alcohol, drug or chemical abuse
• Previous hospitalizations associated with the development of moderate and severe COVID-19.
• Mental illness.
• Receipt of plasma from a person who recovered from COVID-19 (convalescent plasma) up to 14 days before participating in the study, vaccination against SARS-CoV-2 less than 4 weeks before randomization.
• Any conditions that, according to the researcher's, may be a contraindication to the participation in the study.