inclusion criteria: adult, ≥ 18 years of age at the time of consent for inclusion in the sars-cov-2 seronegative population: no history of laboratory-confirmed sars-cov-2 infection (ie, no positive nucleic acid amplification test and no positive antibody test). seronegative for sars-cov-2 at screening (lateral flow test to detect reactivity to the nucleoprotein). medically stable such that, according to the judgment of the investigator, hospitalization within the study period is not anticipated and the participant appears likely to be able to remain on study through the end of protocol-specified follow-up able to understand and comply with study requirements/procedures (if applicable, with assistance by caregiver, surrogate, or legally authorized representative) based on the assessment of the investigator signed informed consent obtained before conducting any study-related procedures contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. previously covid-19 vaccinated participants: prior completion of a 2-dose primary homologous vaccination regimen against sarscov-2 with either azd1222 (2 standard doses as authorized vaccine or as investigational product in a clinical trial with a 4 to 12-week dosing interval) or with an mrna vaccine approved for emergency or conditional use. the second dose in all cases should have been administered at least 3 months prior to first administration of study intervention.

inclusion criteria: adult, ≥ 18 years of age at the time of consent for inclusion in the sars-cov-2 seronegative population: no history of laboratory-confirmed sars-cov-2 infection (ie, no positive nucleic acid amplification test and no positive antibody test). seronegative for sars-cov-2 at screening (lateral flow test to detect reactivity to the nucleoprotein). medically stable such that, according to the judgment of the investigator, hospitalization within the study period is not anticipated and the participant appears likely to be able to remain on study through the end of protocol-specified follow-up able to understand and comply with study requirements/procedures (if applicable, with assistance by caregiver, surrogate, or legally authorized representative) based on the assessment of the investigator signed informed consent obtained before conducting any study-related procedures contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. previously covid-19 vaccinated participants: prior completion of a 2-dose primary homologous vaccination regimen against sarscov-2 with either azd1222 (2 standard doses as authorized vaccine or as investigational product in a clinical trial with a 4 to 12-week dosing interval) or with an mrna vaccine approved for emergency or conditional use. the second dose in all cases should have been administered at least 3 months prior to first administration of study intervention.

inclusion criteria: 1. adult, ≥ 18 years of age at the time of consent for inclusion in the sars-cov-2 seronegative population: 2. no history of laboratory-confirmed sars-cov-2 infection (ie, no positive nucleic acid amplification test and no positive antibody test). 3. seronegative for sars-cov-2 at screening (lateral flow test to detect reactivity to the nucleoprotein). 4. medically stable such that, according to the judgment of the investigator, hospitalization within the study period is not anticipated and the participant appears likely to be able to remain on study through the end of protocol-specified follow-up 5. able to understand and comply with study requirements/procedures (if applicable, with assistance by caregiver, surrogate, or legally authorized representative) based on the assessment of the investigator 6. signed informed consent obtained before conducting any study-related procedures 7. contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. previously covid-19 vaccinated participants: 8. prior completion of a 2-dose primary homologous vaccination regimen against sarscov-2 with either azd1222 (2 standard doses as authorized vaccine or as investigational product in a clinical trial with a 4 to 12-week dosing interval) or with an mrna vaccine approved for emergency or conditional use. the second dose in all cases should have been administered at least 3 months prior to first administration of study intervention.

inclusion criteria: 1. adult, ≥ 18 years of age at the time of consent for inclusion in the sars-cov-2 seronegative population: 2. no history of laboratory-confirmed sars-cov-2 infection (ie, no positive nucleic acid amplification test and no positive antibody test). 3. seronegative for sars-cov-2 at screening (lateral flow test to detect reactivity to the nucleoprotein). 4. medically stable such that, according to the judgment of the investigator, hospitalization within the study period is not anticipated and the participant appears likely to be able to remain on study through the end of protocol-specified follow-up 5. able to understand and comply with study requirements/procedures (if applicable, with assistance by caregiver, surrogate, or legally authorized representative) based on the assessment of the investigator 6. signed informed consent obtained before conducting any study-related procedures 7. contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. previously covid-19 vaccinated participants: 8. prior completion of a 2-dose primary homologous vaccination regimen against sarscov-2 with either azd1222 (2 standard doses as authorized vaccine or as investigational product in a clinical trial with a 4 to 12-week dosing interval) or with an mrna vaccine approved for emergency or conditional use. the second dose in all cases should have been administered at least 3 months prior to first administration of study intervention.