1. positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. 2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. 3. moderate or severe illness and/or fever \>100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. 4. canadian frailty scale score of ≥7 (see appendix 1). 5. history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. 6. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. 7. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. 8. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. 9. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. 10. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. 11. has received systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). 12. has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. 13. has donated ≥450 ml of blood products within 28 days prior to screening. 14. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. 15. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. 16. pregnant. 17. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. 18. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. 19. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. 20. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. 21. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. 22. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.

1. positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. 2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. 3. moderate or severe illness and/or fever \>100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. 4. canadian frailty scale score of ≥7 (see appendix 1). 5. history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. 6. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. 7. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. 8. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. 9. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. 10. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. 11. has received systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). 12. has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. 13. has donated ≥450 ml of blood products within 28 days prior to screening. 14. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. 15. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. 16. pregnant. 17. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. 18. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. 19. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. 20. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. 21. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. 22. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.

positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. moderate or severe illness and/or fever >100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. canadian frailty scale score of ≥7 (see appendix 1). history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. has received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. has donated ≥450 ml of blood products within 28 days prior to screening. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. pregnant. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.

positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. moderate or severe illness and/or fever >100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. canadian frailty scale score of ≥7 (see appendix 1). history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. has received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. has donated ≥450 ml of blood products within 28 days prior to screening. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. pregnant. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.

1. positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. 2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. 3. moderate or severe illness and/or fever >100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. 4. canadian frailty scale score of ≥7 (see appendix 1). 5. history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. 6. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. 7. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. 8. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. 9. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. 10. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. 11. has received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). 12. has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. 13. has donated ≥450 ml of blood products within 28 days prior to screening. 14. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. 15. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. 16. pregnant. 17. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. 18. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. 19. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. 20. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. 21. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. 22. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.

1. positive for sars-cov-2 shedding or self-reported history of prior infection with sars cov-2. 2. seropositive for sars-cov-2, except for 300 subjects in the seropositive cohort in phase 3 only. 3. moderate or severe illness and/or fever >100.4°f/38°c within 1 week before vaccination. screening and/or study vaccination may be rescheduled at the discretion of the investigator. 4. canadian frailty scale score of ≥7 (see appendix 1). 5. history of severe local or systemic reactions to any vaccination or a history of severe allergic reactions. 6. coronavirus vaccines: previous receipt of sars-cov-2 vaccine or other investigational coronavirus vaccine (sars-cov, mers-cov) at any time. 7. investigational non-coronavirus vaccines: previous receipt of an investigational vaccine (non-coronavirus) within 1 year before the planned administration of the first dose of study vaccine. 8. licensed vaccines: participant received or plans to receive: (a) licensed live attenuated vaccines or licensed adjuvanted (non-aluminum compound) vaccine within 28 days before or after planned administration of study vaccine, and (b) other licensed (not noted above) vaccines within 14 days before or after planned administration of study vaccine. 9. immunosuppressive or immunodeficient state, autoimmune diseases, chronic kidney disease (with dialysis), asplenia, recurrent severe infections. 10. individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, e.g., for cancer or an autoimmune disease, or planned receipt throughout the study. 11. has received systemic immunosuppressants or immune-modifying drugs for >14 days in total within 6 months prior to screening (for corticosteroids ≥20 mg/day of prednisone equivalent). 12. has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. 13. has donated ≥450 ml of blood products within 28 days prior to screening. 14. participant received an investigational drug (including investigational drugs for prophylaxis of covid-19) or used an invasive investigational medical device within 30 days. however, participants who received specific anti-sars-cov-2 monoclonal antibody products (e.g., regn-cov2) at any time are permanently excluded, even if such product was given as part of a normal volunteer study. 15. currently enrolled or plans to participate in another investigational study (drug, vaccine, or device) during this study. 16. pregnant. 17. lactating women who are unwilling or unable to withhold breastfeeding and storing milk for 3 days after each vaccination. 18. bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. 19. tattoos or scars at the deltoid sites of im injection that would obscure injection site reactions. 20. behavioral, cognitive, or psychiatric disease that, in the opinion of the principal investigator or his or her representative physician, affects the participant's ability to understand and cooperate with all study protocol requirements. 21. any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history. 22. any other condition that, in the opinion of the principal investigator or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with the study protocol.