Study of the Immunogenicity, Safety and Tolerability of the Convacell Vaccine.

Inclusion Criteria: 1. Healthy men and women aged 18 to 60 years old, inclusive. 2. Written informed consent of the volunteer to participate in the clinical trial; 3. BMI within the range of 18.5 ≤ BWI ≤ 30 kg/m2 with the body weight of not less than 55 kg for men, not less than 45 kg for women and not more than 100 kg for volunteers of both sexes. 4. Verified "healthy" status: no deviations from reference values of standard clinical, laboratory and instrumental examinations. 5. Negative HIV 1\&2, RPR, HВsAg and HCV RNA tests. 6. Hemodynamic and other vital signs are within normal limits (reference intervals are 60-90 beats/min at rest for HR, up to 22 per minute for RR, body temperature from 35.5 to 36.9 °C; systolic blood pressure (SBP) is considered normal in the range of 100-139 mmHg, diastolic blood pressure (DBP) - in the range of 60-89 mmHg); 7. Volunteers able to fulfill requirements of the Protocol (i.e., fill out the patient's diary, come to follow-up visits); 8. Abstinence from alcohol for 14 days before the start of the trial and until the end of participation in the trial; 9. Abstinence from smoking for 48 hours before the start of the trial and during hospitalization; 10. For fertile women - a negative result of the pregnancy test and consent to observe adequate methods of contraception during the trial and at least two months after vaccination; 11. For fertile men - consent to observe adequate methods of contraception during the trial and at least two months after vaccination, except for men after vasectomy with documented azoospermia, and their sexual partners should use methods of contraception that ensure more than 90% reliability or be incapable of conception after a surgical sterilization or have a natural menopause for at least 2 years Exclusion Criteria: 1. History of influenza or acute respiratory viral infection (ARVI) within 2 months before the start of the trial. 2. A serious post-vaccination reaction (temperature above 40 °C, hyperemia or edema more than 8 cm in diameter) or complications (collapse or shock-like condition that developed within 48 hours after vaccination; convulsions accompanied or not accompanied by a fever due to any previous vaccination). 3. Fever, cough, and shortness of breath within 30 days before vaccination. 4. History of COVID-19. 5. Positive result of the COVID-19 PCR test. 6. Body temperature ≥ 37,0°C. 7. History of allergies. 8. Any vaccination within 30 days before the screening. 9. History of leukemia, tuberculosis, cancer, autoimmune diseases. 10. History of Quincke's edema. 11. Positive blood test results for HIV, syphilis, hepatitis B/C. 12. Volunteers who received immunoglobulin during the last three months before the trial. 13. History of long-term use (more than 14 days) of immunosuppressants or other immunomodulatory drugs for six months before the trial. 14. Treatment with glucocorticosteroids, including in small doses, as well as local use of drugs containing steroids (\> 10 mg of prednisolone or its equivalent for more than 14 days before the screening). 15. History of any confirmed or suspected immunosuppressive or immunodeficiency condition. 16. History of splenectomy. 17. History of chronic diseases of the cardiovascular, bronchopulmonary, neuroendocrine systems, the gastrointestinal tract, liver, kidneys, hematopoietic or immune systems, mental disease in the acute stage or in the decompensation stage. 18. Transfusion of blood or blood components within 4 months before screening. 19. History of acute and chronic infectious diseases. 20. Consumption of more than 10 units of alcohol per week or history of alcohol addiction, drug addiction or abuse of pharmaceutical products. 21. Smoking of more than 10 cigarettes per day. 22. Participation in another clinical trial within the last 90 days. 23. Pregnancy or lactation. 24. Coagulopathy, hemophilia, bleeding disorder. 25. Participation in stage I of this trial (for volunteers of stage II). 26. Transfusion of COVID-19 convalescent plasma within 14 days before the screening, COVID-19 vaccination less than 30 days before the screening