Safety and Immunogenicity of Two Different Strengths of the Inactivated COVID-19 Vaccine ERUCOV-VAC

Inclusion Criteria: * healthy Caucasian origin * age between 18 and 55 years * accepting not to participate in another COVID-19 vaccine study until the end of the study * volunteers who do not plan to get a child in the next one year; the volunteer and the partner should use a reliable form of contraception (abstinence, condom, birth control implant, birth control pills used or IUD used by the partner) during the study for at least 1 year * participants must refrain from blood or plasma donation from the time of first vaccination until 3 months after last vaccination * the outcome of the following examinations should be clinically insignificant: medical and surgical history (hypo-, hypertension, allergy, other diseases, major surgery, micturition, defecation, sleep, illness within the last 4 weeks prior to the start of the trial); * life style and habits (consumption of alcohol, nicotine, coffee, tea, coke, special diet, drug abuse) should be normal/acceptable * body temperature, pulse rate, blood pressure, respiratory rate and 12 lead ECG should be normal/acceptable. * physical examination (general state and abnormal findings per system: endocrine/metabolic, allergies, drug sensitivities, head, neck, eyes, ears, nose, throat, cardiovascular, respiratory, gastrointestinal, hepatic/biliary, urogenital, musculoskeletal, lymph nodes, skin, and neurological/psychiatric) should be normal/acceptable * laboratory examination (blood/serum examination: sodium, potassium, calcium, chloride, total protein, albumin, glucose, creatinine, BUN, uric acid, total bilirubin, direct and indirect bilirubin, lipid panel (total cholesterol, triglyceride, HDL, LDL), AST, ALT, GGT, ALP, haemoglobin, haematocrit, erythrocytes, leukocytes, platelet count, prothrombin time (PT) and activated partial thromboplastin time (aPTT); HBsAg, HIV-Ab, HCV-Ab; urine examination: urine color, appearance, specific gravity, pH, protein, glucose, ketones, blood, leukocytes, bilirubin, urobilinogen, nitrites and sediment if erythrocytes or leukocytes are out of the limits ) should be normal/acceptable. * antiSARS CoV 2 total antibody (including COVID-19 IgG and/or IgM) negative in serum. * drug screening negative (amphetamines, cannabinoids, benzodiazepines, cocaine, opioids, barbiturates) * normal body weight in relation to height and age according to BMI (accepted range 18.5 and 30 kg/m2) Exclusion Criteria: * women with a positive blood (β-HCG) pregnancy test * lactating women * history of COVID-19 infection or showing COVID-19 infection symptoms * having had contact to people with known COVID-19 infection in the last 14 days * having fever (\> 37.4oC in the last 24 hours), dry cough or feeling tired and having aches and pains, nasal congestion, runny nose, sore throat and diarrhea. * positive real time RT-PCR COVID-19 test. * persons with autoimmune diseases * allergic diathesis or any clinically significant allergic disease (i.e. asthma) * any condition that might impair the immune response * recent or current immunosuppressive medication * any other vaccine application 30 days before the first dose