inclusion criteria: * adult men and women ≥18 year-old and ≤55-year-old. * signed informed consent. * no respiratory disease within last 21 days prior to first dose administration. * body mass index from 18.0 to 29.0 kg/m2. * negative rt-pcr for sars-cov-2 infection. * negative test for anti-sars-cov-2 igm and igg antibodies. * o2 saturation ≥92% by pulse oximetry. * normal ct scan of thorax. * no symptoms from clinical history and normal physical exam at screening visit. * lab test values within normal ranges for all the following: urinalysis. liver enzymes. renal function tests. cholesterol and triglycerides. fasting glucose. hematology. * negative test for hbsag, anti-hcv and anti-hiv antibodies. negative vdrl test. * normal electrocardiogram. * negative pregnancy test for women with childbearing potential. * agreement of all sexually- active volunteers to use highly effective contraceptives over the study period and up to 30 days after the last administration of the experimental vaccine. * commitment from all participants to keep social distancing, use of mask and frequent hand washing with soap or antibacterial gel during the study period.

inclusion criteria: * adult men and women ≥18 year-old and ≤55-year-old. * signed informed consent. * no respiratory disease within last 21 days prior to first dose administration. * body mass index from 18.0 to 29.0 kg/m2. * negative rt-pcr for sars-cov-2 infection. * negative test for anti-sars-cov-2 igm and igg antibodies. * o2 saturation ≥92% by pulse oximetry. * normal ct scan of thorax. * no symptoms from clinical history and normal physical exam at screening visit. * lab test values within normal ranges for all the following: urinalysis. liver enzymes. renal function tests. cholesterol and triglycerides. fasting glucose. hematology. * negative test for hbsag, anti-hcv and anti-hiv antibodies. negative vdrl test. * normal electrocardiogram. * negative pregnancy test for women with childbearing potential. * agreement of all sexually- active volunteers to use highly effective contraceptives over the study period and up to 30 days after the last administration of the experimental vaccine. * commitment from all participants to keep social distancing, use of mask and frequent hand washing with soap or antibacterial gel during the study period.

inclusion criteria: - adult men and women ≥18 year-old and ≤55-year-old. - signed informed consent. - no respiratory disease within last 21 days prior to first dose administration. - body mass index from 18.0 to 29.0 kg/m2. - negative rt-pcr for sars-cov-2 infection. - negative test for anti-sars-cov-2 igm and igg antibodies. - o2 saturation ≥92% by pulse oximetry. - normal ct scan of thorax. - no symptoms from clinical history and normal physical exam at screening visit. - lab test values within normal ranges for all the following: urinalysis. liver enzymes. renal function tests. cholesterol and triglycerides. fasting glucose. hematology. - negative test for hbsag, anti-hcv and anti-hiv antibodies. negative vdrl test. - normal electrocardiogram. - negative pregnancy test for women with childbearing potential. - agreement of all sexually- active volunteers to use highly effective contraceptives over the study period and up to 30 days after the last administration of the experimental vaccine. - commitment from all participants to keep social distancing, use of mask and frequent hand washing with soap or antibacterial gel during the study period.

inclusion criteria: - adult men and women ≥18 year-old and ≤55-year-old. - signed informed consent. - no respiratory disease within last 21 days prior to first dose administration. - body mass index from 18.0 to 29.0 kg/m2. - negative rt-pcr for sars-cov-2 infection. - negative test for anti-sars-cov-2 igm and igg antibodies. - o2 saturation ≥92% by pulse oximetry. - normal ct scan of thorax. - no symptoms from clinical history and normal physical exam at screening visit. - lab test values within normal ranges for all the following: urinalysis. liver enzymes. renal function tests. cholesterol and triglycerides. fasting glucose. hematology. - negative test for hbsag, anti-hcv and anti-hiv antibodies. negative vdrl test. - normal electrocardiogram. - negative pregnancy test for women with childbearing potential. - agreement of all sexually- active volunteers to use highly effective contraceptives over the study period and up to 30 days after the last administration of the experimental vaccine. - commitment from all participants to keep social distancing, use of mask and frequent hand washing with soap or antibacterial gel during the study period.