history of confirmed infection with sars-cov-2, by positive nasopharyngeal swab or by positive serological test for sars-cov-2 antibodies positive serological test for sars-cov-2 antibodies at screening subjects at high risk of sars-cov-2 infection prior or during the trial, including: subjects with any known exposure in the 4 weeks before enrolment close contacts of suspected or confirmed covid-19 or sars-cov-2 infection cases subjects quarantined for any reason frontline healthcare professionals working in emergency departments, icu and other higher risk healthcare areas positive serological tests for: hepatitis b surface antigen (hbsag) hepatitis c antibodies human immunodeficiency virus (hiv) antibodies subjects with any of the following specific contraindications, even in medical history: type 2 diabetes or glucose intolerance, even if controlled hypertension, even if controlled chronic obstructive pulmonary disease (copd) any cardiac disease, even if not evident at ecg pacemaker use of any investigational drugs/treatments, or enrolment in a clinical trial during the 6 months preceding screening prior administration of any vaccine in the 2 weeks preceding screening administration of any monoclonal or polyclonal antibody product within 4 weeks preceding screening administration of any blood product within 3 months of screening current or prior administration, within the 6 months preceding screening, of immunosuppressants (inhaled, topical skin and/or eye drop-containing corticosteroids; a short course of corticosteroids, defined as ≤20 mg/day prednisone or equivalent for 10 days, and low-dose methotrexate are allowed until 4 weeks prior to screening) any prior major surgery or any chemo- or radiation therapy within 5 years of screening current or suspected immunosuppressive or immunodeficient state, including hiv infection, asplenia, recurrent severe infections active, known, or suspected autoimmune disease (except mild psoriasis, well-controlled autoimmune thyroid disease, vitiligo or stable coeliac disease not requiring immunosuppressive or immunomodulatory therapy) bleeding disorders (e.g. coagulopathy or platelet disorder or coagulation factor deficiency) or prior history of significant bleeding or bruising following im injections or venipuncture history of seizures or mental illness history of allergy to vaccines or of severe allergic reaction of any kind metal implants within 20 cm of the planned site(s) of injection presence of keloid scar formation or hypertrophic scar, or other clinically significant medical condition at the planned site(s) of injection any abnormality or permanent body art (e.g. tattoos) that would interfere with the ability to observe local reactions at the injection site in the deltoid area history of alcohol or drug abuse during the 12 months preceding the screening pregnancy (i.e. positive pregnancy test) or willingness/intention to become pregnant during the study breastfeeding any other clinically relevant disease and condition that, in the opinion of the investigator, may jeopardize efficacy or safety assessments or may compromise the subject's safety during trial participation.

history of confirmed infection with sars-cov-2, by positive nasopharyngeal swab or by positive serological test for sars-cov-2 antibodies positive serological test for sars-cov-2 antibodies at screening subjects at high risk of sars-cov-2 infection prior or during the trial, including: subjects with any known exposure in the 4 weeks before enrolment close contacts of suspected or confirmed covid-19 or sars-cov-2 infection cases subjects quarantined for any reason frontline healthcare professionals working in emergency departments, icu and other higher risk healthcare areas positive serological tests for: hepatitis b surface antigen (hbsag) hepatitis c antibodies human immunodeficiency virus (hiv) antibodies subjects with any of the following specific contraindications, even in medical history: type 2 diabetes or glucose intolerance, even if controlled hypertension, even if controlled chronic obstructive pulmonary disease (copd) any cardiac disease, even if not evident at ecg pacemaker use of any investigational drugs/treatments, or enrolment in a clinical trial during the 6 months preceding screening prior administration of any vaccine in the 2 weeks preceding screening administration of any monoclonal or polyclonal antibody product within 4 weeks preceding screening administration of any blood product within 3 months of screening current or prior administration, within the 6 months preceding screening, of immunosuppressants (inhaled, topical skin and/or eye drop-containing corticosteroids; a short course of corticosteroids, defined as ≤20 mg/day prednisone or equivalent for 10 days, and low-dose methotrexate are allowed until 4 weeks prior to screening) any prior major surgery or any chemo- or radiation therapy within 5 years of screening current or suspected immunosuppressive or immunodeficient state, including hiv infection, asplenia, recurrent severe infections active, known, or suspected autoimmune disease (except mild psoriasis, well-controlled autoimmune thyroid disease, vitiligo or stable coeliac disease not requiring immunosuppressive or immunomodulatory therapy) bleeding disorders (e.g. coagulopathy or platelet disorder or coagulation factor deficiency) or prior history of significant bleeding or bruising following im injections or venipuncture history of seizures or mental illness history of allergy to vaccines or of severe allergic reaction of any kind metal implants within 20 cm of the planned site(s) of injection presence of keloid scar formation or hypertrophic scar, or other clinically significant medical condition at the planned site(s) of injection any abnormality or permanent body art (e.g. tattoos) that would interfere with the ability to observe local reactions at the injection site in the deltoid area history of alcohol or drug abuse during the 12 months preceding the screening pregnancy (i.e. positive pregnancy test) or willingness/intention to become pregnant during the study breastfeeding any other clinically relevant disease and condition that, in the opinion of the investigator, may jeopardize efficacy or safety assessments or may compromise the subject's safety during trial participation.

1. history of confirmed infection with sars-cov-2, by positive nasopharyngeal swab or by positive serological test for sars-cov-2 antibodies 2. positive serological test for sars-cov-2 antibodies at screening 3. subjects at high risk of sars-cov-2 infection prior or during the trial, including: 1. subjects with any known exposure in the 4 weeks before enrolment 2. close contacts of suspected or confirmed covid-19 or sars-cov-2 infection cases 3. subjects quarantined for any reason 4. frontline healthcare professionals working in emergency departments, icu and other higher risk healthcare areas 4. positive serological tests for: 1. hepatitis b surface antigen (hbsag) 2. hepatitis c antibodies 3. human immunodeficiency virus (hiv) antibodies 5. subjects with any of the following specific contraindications, even in medical history: 1. type 2 diabetes or glucose intolerance, even if controlled 2. hypertension, even if controlled 3. chronic obstructive pulmonary disease (copd) 4. any cardiac disease, even if not evident at ecg 5. pacemaker 6. use of any investigational drugs/treatments, or enrolment in a clinical trial during the 6 months preceding screening 7. prior administration of any vaccine in the 2 weeks preceding screening 8. administration of any monoclonal or polyclonal antibody product within 4 weeks preceding screening 9. administration of any blood product within 3 months of screening 10. current or prior administration, within the 6 months preceding screening, of immunosuppressants (inhaled, topical skin and/or eye drop-containing corticosteroids; a short course of corticosteroids, defined as ≤20 mg/day prednisone or equivalent for 10 days, and low-dose methotrexate are allowed until 4 weeks prior to screening) 11. any prior major surgery or any chemo- or radiation therapy within 5 years of screening 12. current or suspected immunosuppressive or immunodeficient state, including hiv infection, asplenia, recurrent severe infections 13. active, known, or suspected autoimmune disease (except mild psoriasis, well-controlled autoimmune thyroid disease, vitiligo or stable coeliac disease not requiring immunosuppressive or immunomodulatory therapy) 14. bleeding disorders (e.g. coagulopathy or platelet disorder or coagulation factor deficiency) or prior history of significant bleeding or bruising following im injections or venipuncture 15. history of seizures or mental illness 16. history of allergy to vaccines or of severe allergic reaction of any kind 17. metal implants within 20 cm of the planned site(s) of injection 18. presence of keloid scar formation or hypertrophic scar, or other clinically significant medical condition at the planned site(s) of injection 19. any abnormality or permanent body art (e.g. tattoos) that would interfere with the ability to observe local reactions at the injection site in the deltoid area 20. history of alcohol or drug abuse during the 12 months preceding the screening 21. pregnancy (i.e. positive pregnancy test) or willingness/intention to become pregnant during the study 22. breastfeeding 23. any other clinically relevant disease and condition that, in the opinion of the investigator, may jeopardize efficacy or safety assessments or may compromise the subject's safety during trial participation.

1. history of confirmed infection with sars-cov-2, by positive nasopharyngeal swab or by positive serological test for sars-cov-2 antibodies 2. positive serological test for sars-cov-2 antibodies at screening 3. subjects at high risk of sars-cov-2 infection prior or during the trial, including: 1. subjects with any known exposure in the 4 weeks before enrolment 2. close contacts of suspected or confirmed covid-19 or sars-cov-2 infection cases 3. subjects quarantined for any reason 4. frontline healthcare professionals working in emergency departments, icu and other higher risk healthcare areas 4. positive serological tests for: 1. hepatitis b surface antigen (hbsag) 2. hepatitis c antibodies 3. human immunodeficiency virus (hiv) antibodies 5. subjects with any of the following specific contraindications, even in medical history: 1. type 2 diabetes or glucose intolerance, even if controlled 2. hypertension, even if controlled 3. chronic obstructive pulmonary disease (copd) 4. any cardiac disease, even if not evident at ecg 5. pacemaker 6. use of any investigational drugs/treatments, or enrolment in a clinical trial during the 6 months preceding screening 7. prior administration of any vaccine in the 2 weeks preceding screening 8. administration of any monoclonal or polyclonal antibody product within 4 weeks preceding screening 9. administration of any blood product within 3 months of screening 10. current or prior administration, within the 6 months preceding screening, of immunosuppressants (inhaled, topical skin and/or eye drop-containing corticosteroids; a short course of corticosteroids, defined as ≤20 mg/day prednisone or equivalent for 10 days, and low-dose methotrexate are allowed until 4 weeks prior to screening) 11. any prior major surgery or any chemo- or radiation therapy within 5 years of screening 12. current or suspected immunosuppressive or immunodeficient state, including hiv infection, asplenia, recurrent severe infections 13. active, known, or suspected autoimmune disease (except mild psoriasis, well-controlled autoimmune thyroid disease, vitiligo or stable coeliac disease not requiring immunosuppressive or immunomodulatory therapy) 14. bleeding disorders (e.g. coagulopathy or platelet disorder or coagulation factor deficiency) or prior history of significant bleeding or bruising following im injections or venipuncture 15. history of seizures or mental illness 16. history of allergy to vaccines or of severe allergic reaction of any kind 17. metal implants within 20 cm of the planned site(s) of injection 18. presence of keloid scar formation or hypertrophic scar, or other clinically significant medical condition at the planned site(s) of injection 19. any abnormality or permanent body art (e.g. tattoos) that would interfere with the ability to observe local reactions at the injection site in the deltoid area 20. history of alcohol or drug abuse during the 12 months preceding the screening 21. pregnancy (i.e. positive pregnancy test) or willingness/intention to become pregnant during the study 22. breastfeeding 23. any other clinically relevant disease and condition that, in the opinion of the investigator, may jeopardize efficacy or safety assessments or may compromise the subject's safety during trial participation.