ABDALA Clinical Study

INTERVENTION: CIGB‐66 Group 1: CIGB‐66 (RBD 25 mcg + aluminum hydroxide 0.30 mg); 0.5 mL intramuscularly in the deltoid region (0‐14‐28 days schedule). Group 2: CIGB‐66 (RBD 50 mcg + aluminum hydroxide 0.30 mg); 0.5 mL intramuscularly in the deltoid region (0‐14‐28 days schedule). Group 3: Placebo; 0.5 mL intramuscularly in the deltoid region (0‐14‐28 days schedule). Group 4: CIGB‐66 (RBD 25 mcg + aluminum hydroxide 0.30 mg); 0.5 mL intramuscularly in the deltoid region (schedule 0‐28‐56 days). Group 5: CIGB‐66 (RBD 50 mcg + aluminum hydroxide 0.30 mg); 0.5 mL intramuscularly in the deltoid region (schedule 0‐28‐56 days). Group 6: Placebo; 0.5 mL intramuscularly in the deltoid region (schedule 0‐28‐56 days). These interventions will be carried out during the first stage (phase I). Subsequently, an intermediate analysis will be carried out where doses and immunization schedules for phase II will be defined. Immunogenicity, Vaccine CONDITION: COVID‐19 COVID‐19 ; COVID‐19 Disease Prevention PRIMARY OUTCOME: 1. Safety ‐ Adverse clinical events‐AE (They will be measured as: ‐Occurrence of AE (Yes, No), ‐Description of AE (name of event), ‐Intensity of AE (mild, moderate, severe), ‐Causality relationship (no related, doubtful, possible, probable, definitive), ‐Measures taken (None, Administration of any pharmacological therapy, Addition of a non‐pharmacological therapy, Study exit, Hospitalization / prolongation of hospitalization), ‐Result (Completely resolved, Resolved with sequelae, Conditions in improvement, Condition present and unchanged, Worsening, Death caused by this event)). Measurement time: before the administration of each dose of the research product, in the first hour after inoculation of the product (in each dose), at 24, 48 and 72 hours, and on the 7th day. 2. Proportion of subjects with seroconversion of anti‐RBD IgG antibodies to SARS‐CoV‐2 (seroconversion will be considered as that >= 4 times the initial determination of the antibody titer). Measurement time: on days 28 and 42 (for the short scheme 0‐14‐28) and 28, 56 and 70 (for the long scheme 0‐28‐56), with respect to the baseline time. SECONDARY OUTCOME: 1. Specific anti‐RBD IgG antibodies (geometric mean). Measurement time: on days 0, 28 and 42 (for the short vaccination schedule: 0‐14‐28) and 0, 28, 56 and 70 (for the long schedule: 0‐28‐56). 2. ACE2 inhibition (by ELISA ‐ Enzyme‐linked immunoadsorption assay). Measurement time: on days 0, 28 and 42 (for the short vaccination scheme) and 0, 28, 56 and 70 (for the long scheme). 3. Humoral response of specific anti‐RBD IgM antibodies. Measurement time: on days 0, 28 and 42 (for the short vaccination scheme) and 0, 28, 56 and 70 (for the long scheme). INCLUSION CRITERIA: 1) Individuals aged between 19 and 54 years, both inclusive (for phase I) and between 19 and 80 years old, both inclusive (for phase II). 2) Physical examination without significant alterations. 3) Hematological and blood chemistry determinations within or outside normal ranges, without clinical relevance (only for phase I). 4) Voluntariness of the subject by signing the informed consent.