An Open Comprative Study of the Prophylactic Efficacy and a Non-comparative Study of the Immunogenicity and Safety of the Inactivated Whole-virion Concentrated Purified Coronavirus Vaccine (CoviVac)

Inclusion Criteria: * Volunteers must meet the following inclusion criteria: Type of participants \* Healthy volunteers or volunteers with a history of stable diseases that do not meet any of the criteria for non-inclusion in the study. Age at the time of signing the Informed Consent \* from ≥ 18 to \< 60 years. Paul \* Male or female. The volunteers of the study group must meet the following additional inclusion criteria: * Written Informed consent of volunteers to participate in a clinical trial. * Volunteers who are able to fulfill Protocol requirements (i.e. answer phone calls, fill out a Self-observation Diary, come to control visits). * For women capable of childbirth - a negative pregnancy test and consent to adhere to adequate methods of contraception (use of contraceptives within a month after the second vaccination). Women should use methods of contraception with a reliability of more than 90% (cervical caps with spermicide, diaphragms with spermicide, condoms, intrauterine spirals), or be sterile, or in a postmenopausal state. * For men capable of conception - consent to adhere to adequate methods of contraception (use of contraceptives within a month after the second vaccination). Men and their sexual partners should use methods of contraception with a reliability of more than 90% (cervical caps with spermicide, diaphragms with spermicide, condoms, intrauterine spirals), or be sterile. Exclusion Criteria: * Volunteers cannot be included in the study if any of the following criteria are present: SARS-CoV-2 infection \* A case of established COVID-19 disease confirmed by PCR and/or ELISA in the last 6 months. Diseases or medical conditions * Severe and/or uncontrolled diseases of the cardiovascular, bronchopulmonary, neuroendocrine systems, gastrointestinal tract, liver, kidneys, hematopoietic, immune systems. * Is registered at the dispensary for tuberculosis, leukemia, oncological diseases, autoimmune diseases. • Any confirmed or suspected immunosuppressive or immunodeficiency condition in the anamnesis. * Splenectomy in the anamnesis. * Neutropenia (decrease in the absolute number of neutrophils less than 1000/mm3), agranulocytosis, significant blood loss, severe anemia (hemoglobin less than 80 g/l) according to anamnesis. * Anorexia. Prior or concomitant therapy * Vaccination with any vaccine carried out within 30 days before vaccination / the first dose of the studied vaccine or planned administration within 30 days after vaccination / the last dose of the studied vaccine. * Prior vaccination with an experimental or registered vaccine that may affect the interpretation of the study data (any coronavirus or SARS vaccines). * Long-term use (more than 14 days) of immunosuppressants or other immunomodulatory drugs (immunoregulatory peptides, cytokines, interferons, immune system effector proteins (immunoglobulins), interferon inducers (cycloferon) during the six months preceding the study, according to anamnesis. * Treatment with glucocorticosteroids (≥ 20 mg of prednisone, or an analog, for more than 15 days during the last month). * Volunteers who received immunoglobulin preparations or blood transfusion during the last 3 months before the start of the study according to anamnesis. Other non-inclusion criteria \* Pregnancy or breast-feeding. Participation in any other clinical trial within the last 3 months. Volunteers of the study group cannot be included in the study if any of the following criteria are present: Diseases or medical conditions * Serious post-vaccination reaction (temperature above 40 C, hyperemia or edema more than 8 cm in diameter) or complication (collapse or shock-like condition that developed within 48 hours after vaccination; convulsions, accompanied or not accompanied by a feverish state) to any previous vaccination. * Burdened allergic history (anaphylactic shock, Quincke's edema, polymorphic exudative eczema, serum sickness in the anamnesis, hypersensitivity or allergic reactions to the introduction of any vaccines in the anamnesis, known allergic reactions to vaccine components, etc.)• * Guillain-Barre syndrome (acute polyradiculitis) in the anamnesis. * The axillary temperature at the time of vaccination is more than 37.0 ° C. * Acute infectious diseases (recovery earlier than 4 weeks before vaccination) according to anamnesis. * Donation of blood or plasma (in the amount of 450 ml or more) less than 2 months before inclusion in the study. Exclusion criteria: * Withdrawal of Informed consent by a volunteer; \* The volunteer was included in violation of the inclusion/non-inclusion criteria of the Protocol; • Any condition of a volunteer that requires, in the reasoned opinion of a medical researcher, the withdrawal of a volunteer from the study; \* The established fact of pregnancy before the second vaccination; \* The volunteer refuses to cooperate or is undisciplined (for example, failure to attend a scheduled visit without warning the researcher and/or loss of communication with the volunteer), or dropped out of observation; \* For administrative reasons (termination of the study by the Sponsor or regulatory authorities), as well as in case of gross violations of the Protocol that may affect the results of the study.