1. laboratory-confirmed sars-cov-2 infection (pcr+ within 5 days prior to first study vaccination with results available before randomization) or positive anti-s protein antibody to sars-cov-2 at screening. 2. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. 3. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. 4. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. 5. any known allergies to products contained in the investigational product. 6. any history of anaphylaxis to any prior vaccine. 7. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. 8. chronic administration (defined as \> 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. 9. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. 10. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). 11. participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. 12. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. 13. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). 14. study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

1. laboratory-confirmed sars-cov-2 infection (pcr+ within 5 days prior to first study vaccination with results available before randomization) or positive anti-s protein antibody to sars-cov-2 at screening. 2. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. 3. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. 4. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. 5. any known allergies to products contained in the investigational product. 6. any history of anaphylaxis to any prior vaccine. 7. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. 8. chronic administration (defined as \> 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. 9. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. 10. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). 11. participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. 12. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. 13. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). 14. study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

laboratory-confirmed sars-cov-2 infection (pcr+ within 5 days prior to first study vaccination with results available before randomization) or positive anti-s protein antibody to sars-cov-2 at screening. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. any known allergies to products contained in the investigational product. any history of anaphylaxis to any prior vaccine. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

laboratory-confirmed sars-cov-2 infection (pcr+ within 5 days prior to first study vaccination with results available before randomization) or positive anti-s protein antibody to sars-cov-2 at screening. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. any known allergies to products contained in the investigational product. any history of anaphylaxis to any prior vaccine. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

laboratory-confirmed sars-cov-2 infection (polymerase chain reaction + within 5 days prior to first study vaccination with results available before randomization) or positive serology (eg, anti-nucleocapsid or anti-s protein antibody) to sars-cov-2 infection at any time prior to randomization. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. any known allergies to products contained in the investigational product. any history of anaphylaxis to any prior vaccine. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

laboratory-confirmed sars-cov-2 infection (polymerase chain reaction + within 5 days prior to first study vaccination with results available before randomization) or positive serology (eg, anti-nucleocapsid or anti-s protein antibody) to sars-cov-2 infection at any time prior to randomization. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. any known allergies to products contained in the investigational product. any history of anaphylaxis to any prior vaccine. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

1. laboratory-confirmed sars-cov-2 infection (polymerase chain reaction + within 5 days prior to first study vaccination with results available before randomization) or positive serology (eg, anti-nucleocapsid or anti-s protein antibody) to sars-cov-2 infection at any time prior to randomization. 2. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. 3. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. 4. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. 5. any known allergies to products contained in the investigational product. 6. any history of anaphylaxis to any prior vaccine. 7. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. 8. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. 9. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. 10. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). 11. participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. 12. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. 13. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). 14. study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).

1. laboratory-confirmed sars-cov-2 infection (polymerase chain reaction + within 5 days prior to first study vaccination with results available before randomization) or positive serology (eg, anti-nucleocapsid or anti-s protein antibody) to sars-cov-2 infection at any time prior to randomization. 2. previous receipt of any investigational or authorized/approved vaccine, prophylactic or therapeutic agent for the prevention or treatment of covid-19. 3. participation in research involving receipt of an investigational product (drug/biologic/device) within 90 days prior to the first study vaccination. 4. received influenza vaccination within 14 days prior to first study vaccination, or any other vaccine within 30 days prior to first study vaccination. 5. any known allergies to products contained in the investigational product. 6. any history of anaphylaxis to any prior vaccine. 7. autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) requiring ongoing immunomodulatory therapy. 8. chronic administration (defined as > 14 continuous days) of immunosuppressant, systemic glucocorticoids, or other immune-modifying drugs within 90 days prior to first study vaccination. 9. received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to first study vaccination. 10. active cancer (malignancy) on therapy within 3 years prior to first study vaccination (with the exception of adequately treated non-melanomatous skin carcinoma or lentigo maligna and uterine cervical carcinoma in situ without evidence of disease, at the discretion of the investigator). 11. participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the end of study. 12. suspected or known history of alcohol abuse or drug addiction within 2 years prior to the first study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance. 13. any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting). 14. study team member or immediate family member of any study team member (inclusive of sponsor, contract research organization, and study site personnel involved in the conduct or planning of the study).