participants meeting any of the following criteria will be excluded from the study: 1. confirmed sars-cov-2 infection \< 16 weeks prior to any study vaccine dose. 2. pregnant and breastfeeding participants. 3. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. 4. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). 5. a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate or nanolipid particles. 6. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1, 2 and 4). 7. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. 8. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. 9. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. 10. advanced liver or kidney diseases. 11. advanced (cd4 count \< 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. 12. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for \>14 days in total within 6 months prior to any study vaccine dose (for corticosteroids = 20 mg \> / = day of prednisone equivalent). note: topical medications are allowed. 13. received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. 14. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. 15. study personnel or an immediate family member or household member of study personnel. 16. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as \> / = 38.0 degrees celsius/100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19. 17. plan to receive a covid-19 booster vaccine outside of the study within the next 180 days. (for subjects in stage 4 only)

participants meeting any of the following criteria will be excluded from the study: 1. confirmed sars-cov-2 infection \< 16 weeks prior to any study vaccine dose. 2. pregnant and breastfeeding participants. 3. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. 4. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). 5. a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate or nanolipid particles. 6. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1, 2 and 4). 7. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. 8. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. 9. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. 10. advanced liver or kidney diseases. 11. advanced (cd4 count \< 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. 12. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for \>14 days in total within 6 months prior to any study vaccine dose (for corticosteroids = 20 mg \> / = day of prednisone equivalent). note: topical medications are allowed. 13. received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. 14. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. 15. study personnel or an immediate family member or household member of study personnel. 16. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as \> / = 38.0 degrees celsius/100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19. 17. plan to receive a covid-19 booster vaccine outside of the study within the next 180 days. (for subjects in stage 4 only)

participants meeting any of the following criteria will be excluded from the study: confirmed sars-cov-2 infection < 16 weeks prior to any study vaccine dose. pregnant and breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1, 2 and 4). received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids = 20 mg > / = day of prednisone equivalent). note: topical medications are allowed. received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius/100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19. plan to receive a covid-19 booster vaccine outside of the study within the next 180 days. (for subjects in stage 4 only)

participants meeting any of the following criteria will be excluded from the study: confirmed sars-cov-2 infection < 16 weeks prior to any study vaccine dose. pregnant and breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1, 2 and 4). received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids = 20 mg > / = day of prednisone equivalent). note: topical medications are allowed. received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius/100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19. plan to receive a covid-19 booster vaccine outside of the study within the next 180 days. (for subjects in stage 4 only)

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate, or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1 and 2). received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg), polysorbate, or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment (for subjects in stages 1 and 2). received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg) or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg) or nanolipid particles. a history of myocarditis or pericarditis at any time prior to enrollment. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg) or nanolipid particles. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.

participants meeting any of the following criteria will be excluded from the study: confirmed severe acute respiratory syndrome coronavirus 2 (sars-cov-2) infection < 16 weeks prior to any study vaccine dose. pregnant or breastfeeding participants. prior administration of an investigational coronavirus vaccine at any time or sars-cov-2 immunoglobulin, monoclonal antibody or plasma antibody therapy in the preceding 3 months. note: subjects that participated in clinical trials of products that are now fda approved/authorized are allowed to participate. current/planned simultaneous participation in another interventional study or receipt of any investigational study product within 28 days prior to vaccine study dose(s). a history of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine, polyethylene glycol (peg) or nanolipid particles. received or plans to receive a vaccine within 28 days prior to or after any dose of study vaccine. note: receipt of seasonal influenza vaccine is allowed at any time. bleeding disorder diagnosed by a healthcare provider (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or bleeding difficulties with intramuscular injections or blood draws. current or previous diagnosis of an immunocompromising condition or other immunosuppressive condition. advanced liver or kidney diseases. advanced (cd4 count < 200) and/or untreated hiv, untreated hepatitis b or untreated hepatitis c. received oral, intramuscular or intravenous systemic immunosuppressants, or immune-modifying drugs for >14 days in total within 6 months prior to any study vaccine dose (for corticosteroids > / = 20 mg/day of prednisone equivalent). received immunoglobulin or blood-derived products, within 3 months prior any study vaccine dose. received chemotherapy, immunotherapy or radiation therapy within 6 months prior to any study vaccine dose. study personnel or an immediate family member or household member of study personnel. is acutely ill or febrile 72 hours prior to or at vaccine dosing (fever defined as > / = 38.0 degrees celsius /100.4 degrees fahrenheit). participants meeting this criterion may be rescheduled within the relevant window periods. note: afebrile participants with minor illnesses can be enrolled at the discretion of the investigator, as long as the illness is not suggestive of covid-19.