inclusion criteria: 1. signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. 2. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months (pfizer at least (5) months) prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. 3. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. 4. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. 5. female subjects of non-childbearing potential may be enrolled. 6. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. 7. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. 8. must be able to read, understand, and complete questionnaires and diary entries. 9. plans to reside within study area for the duration of the study. 10. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: 1. signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. 2. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months (pfizer at least (5) months) prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. 3. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. 4. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. 5. female subjects of non-childbearing potential may be enrolled. 6. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. 7. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. 8. must be able to read, understand, and complete questionnaires and diary entries. 9. plans to reside within study area for the duration of the study. 10. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months (pfizer at least (5) months) prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months (pfizer at least (5) months) prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 3-16 weeks apart. the last dose of the previous vaccine must have been administered at least three (3) months prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 1 month apart. the last dose of the previous vaccine must have been administered at least three (3) months prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and urine pregnancy test must be negative on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.

inclusion criteria: signed and dated informed consent/assent after reading the consent/assent form and having adequate opportunity to discuss the study with an investigator or designee. documented fully vaccinated with primary series of a comparator vaccine. primary immunization is defined as 2 doses spaced approximately 1 month apart. the last dose of the previous vaccine must have been administered at least three (3) months prior to day 1, taking into consideration the current local and national regulations, and according to details related to individual comparators provided in relevant sub-studies. documentation, such as the national health service (nhs) covid pass, united states centers for disease control vaccine card, or equivalent documentation (e.g., medical records, vaccine passport; in accordance with local approved vaccination record documentation) will be required for proof of vaccination, vaccine manufacturer and vaccination dates. no clinically significant health problems that could affect the safety of the subject, as determined by the investigator by medical history, laboratory tests and physical examination. may have a stable pre-existing medical condition that did not require significant change in medication or hospitalization in 3 months before screening or which, in the judgement of the investigator is unlikely to require a significant change in therapy or hospitalization for worsening disease in the 3 months after day 1. negative sars-cov-2 reverse transcriptase-polymerase chain reaction (rt-pcr) or antigen test within 24-48 hours prior to receipt of injections on day 1. female subjects of non-childbearing potential may be enrolled. males and wocbp, 16 years or older, may be enrolled in the study if they are willing to practice abstinence from sexual intercourse or are willing to use acceptable methods of contraception as described below, from the time of signing the informed consent/assent during the screening period through study product injection on day 1 and until completion of day 29. acceptable methods of contraception should be consistent with local availability/regulations regarding the use of contraceptive methods for those participating in clinical trials. for wocbp, a serum or urine pregnancy test must be negative at screening and urine pregnancy test must be negative on the day of study product injection. must be able to read, understand, and complete questionnaires and diary entries. plans to reside within study area for the duration of the study. able to comply with study procedures for the full duration of the study, in the opinion of the investigator.