This is a Double-blind, Placebo-controlled, Randomized Study of the Tolerability, Safety and Immunogenicity of an Inactivated Whole Virion Concentrated Purified Vaccine (CoviVac) Against Covid-19

Inclusion criteria: Volunteers must meet the following inclusion criteria: * Healthy volunteers (men and women) aged 18-60; * Written informed consent of volunteers to participate in a clinical trial; * Volunteers who are able to comply with the requirements of the Protocol (i.e. filling out the Self-Observation Diary, come to control visits); * For women capable of childbearing, a negative pregnancy test and consent to adhere to adequate contraceptive methods (use of contraceptives within six months after the second vaccination). Women should use contraceptive methods that are more than 90% reliable (cervical caps with spermicide, diaphragms with spermicide, condoms, intrauterine devices), or be sterile or postmenopausal. * For fertile men, consent to adhere to adequate contraceptive methods for six months after the second vaccination. Men and their sexual partners must use contraceptive methods with more than 90% reliability (cervical caps with spermicide, diaphragms with spermicide, condoms, intrauterine devices), or be sterile. Non-inclusion criteria: Volunteers cannot be included in the study if any of the following criteria are met: * Medical staff of clinics and polyclinics; * A history of severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS) or other coronavirus infection (HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1); * History of contacts with confirmed or suspected cases of SARS-CoV-2 infection within 1 month; * Positive IgM or IgG to SARS-CoV-2, found at screening (for volunteers of Phases I and II); * Positive PCR test for SARS-CoV-2 at screening; * Clinically and/or laboratory (according to PCR) confirmed disease with SARS-CoV-2 coronavirus at the current time or in history; * Serious post-vaccination reaction (temperature above 40 C, hyperemia or edema more than 8 cm in diameter) or complication (collapse or shock-like state that developed within 48 hours after vaccination; convulsions, accompanied or not accompanied by a febrile state) to any previous vaccination in history; * Aggravated allergic history (anaphylactic shock, Quincke's edema, polymorphic exudative eczema, atopy, history of serum sickness, history of hypersensitivity or allergic reactions to the administration of any vaccines, known allergic reactions to vaccine components, etc.); * History of Guillain-Barré syndrome (acute polyradiculitis); * Previous vaccination with rabies vaccines less than 2 months before immunization or planned vaccination with rabies vaccines within 1 month after immunization with investigational vaccines; * Vaccination with any other vaccine within 1 month preceding vaccination; * A history of leukemia, tuberculosis, cancer, autoimmune diseases; * Positive blood test for HIV, syphilis, hepatitis B/C; * Volunteers who received immunoglobulin preparations or blood transfusions within the last 3 months prior to the start of the study based on the history; * Long-term use (more than 14 days) of immunosuppressants or other immunomodulatory drugs during the six months preceding the study, according to the history; * Any history of any confirmed or suspected immunosuppressive or immunodeficient condition; * Chronic diseases of the cardiovascular, bronchopulmonary, neuroendocrine systems, gastrointestinal tract, liver, kidneys, hematopoietic, immune systems, mental illness in exacerbation stage or decompensation stage (recovery earlier than 4 weeks before vaccination) in history; * Disorder of blood clotting, a tendency to thrombosis in the anamnesis; * Progressive neurological pathology, a history of convulsive syndrome; * Diabetes mellitus, hyperthyroidism or other endocrine diseases in history; * Treatment with glucocorticosteroids, including low doses, as well as topical use of drugs containing steroids (\> 10 mg prednisolone, or an equivalent, for more than 14 days in the last three months); * According to the anamnesis, the volunteer was/is registered in a tuberculosis dispensary and/or a narcological dispensary and/or a neuropsychiatric dispensary and/or others; * Acute infectious diseases (recovery earlier than 4 weeks before vaccination) according to the history; * Taking more than 10 units of alcohol per week or anamnestic information about alcoholism, drug addiction, or drug abuse; * Smoking more than 10 cigarettes a day; * Participation in any other clinical study within the last 3 months; * Pregnancy or breastfeeding; * Axillary temperature at the time of vaccination is more than 37.0 °C; * Body mass index less than 18 or more than 28 kg/m2; * Serious concomitant diseases or pathological conditions not listed above, which, according to the investigator, could complicate the evaluation of the study results, including pathological deviations from the age norms and laboratory norms of blood and urine parameters, clinically significant, according to the investigator. Exclusion criteria: * Withdrawal of informed consent by a volunteer; * Serious adverse events or adverse events that do not meet the criteria for severity, the development of which, in the opinion of the investigator, may be detrimental to the health or well-being of the volunteer; * The need for procedures and/or drug treatment not permitted by the Study Protocol; * The volunteer was included in violation of the inclusion/non-inclusion criteria of the Protocol; * The emergence of non-inclusion criteria during the study; * The need for surgical intervention; * Any condition in a volunteer requiring, in the reasonable opinion of the investigating physician, the withdrawal of the volunteer from the study; * The volunteer refuses to cooperate or is undisciplined (for example, not showing up for a planned visit without warning the investigator and/or losing contact with the volunteer), or has dropped out of observation; * For administrative reasons (termination of the study by the Sponsor or regulatory authorities), as well as for gross violations of the protocol that could affect the study results.