inclusion criteria: 1. healthy adult male and female volunteers between 18 and 65 years of age, inclusive. 2. participants who received a primary janssen ad26.cov2.s vaccine ≥ 60 days prior to receiving the study vaccine. 3. body mass index within the range 18 - 32 kg/m2 both inclusive. 4. participants who, judged by the investigator, are in stable health as determined by their pre-study medical history, physical examination, and clinical laboratory tests. 5. female participants must be either of non-childbearing potential, i.e., surgically sterilized (defined as having undergone hysterectomy and/or bilateral oophorectomy and/or bilateral salpingectomy; tubal ligation alone is not considered sufficient) or one year postmenopausal; or, if of childbearing potential, they must be abstinent or have used adequate contraceptive precautions for 30 days prior to receiving the study vaccination and 84 days post-vaccine. 6. sexually active male participants who are considered sexually fertile must agree to use a barrier method of contraception during sexual activity with a female of childbearing potential from the time of vaccination until at least 84 days after the vaccination. 7. participants must provide written informed consent or their legal representative must understand and give written consent to the procedure. 8. participants must be willing and able to comply with all the required study visits and follow-up required by this protocol, and be able to complete the diary card after vaccination or have a caregiver available to assist with these matters.

inclusion criteria: 1. healthy adult male and female volunteers between 18 and 65 years of age, inclusive. 2. participants who received a primary janssen ad26.cov2.s vaccine ≥ 60 days prior to receiving the study vaccine. 3. body mass index within the range 18 - 32 kg/m2 both inclusive. 4. participants who, judged by the investigator, are in stable health as determined by their pre-study medical history, physical examination, and clinical laboratory tests. 5. female participants must be either of non-childbearing potential, i.e., surgically sterilized (defined as having undergone hysterectomy and/or bilateral oophorectomy and/or bilateral salpingectomy; tubal ligation alone is not considered sufficient) or one year postmenopausal; or, if of childbearing potential, they must be abstinent or have used adequate contraceptive precautions for 30 days prior to receiving the study vaccination and 84 days post-vaccine. 6. sexually active male participants who are considered sexually fertile must agree to use a barrier method of contraception during sexual activity with a female of childbearing potential from the time of vaccination until at least 84 days after the vaccination. 7. participants must provide written informed consent or their legal representative must understand and give written consent to the procedure. 8. participants must be willing and able to comply with all the required study visits and follow-up required by this protocol, and be able to complete the diary card after vaccination or have a caregiver available to assist with these matters.

inclusion criteria: healthy adult male and female volunteers between 18 and 65 years of age, inclusive. participants who received a primary janssen ad26.cov2.s vaccine ≥ 60 days prior to receiving the study vaccine. body mass index within the range 18 - 32 kg/m2 both inclusive. participants who, judged by the investigator, are in stable health as determined by their pre-study medical history, physical examination, and clinical laboratory tests. female participants must be either of non-childbearing potential, i.e., surgically sterilized (defined as having undergone hysterectomy and/or bilateral oophorectomy and/or bilateral salpingectomy; tubal ligation alone is not considered sufficient) or one year postmenopausal; or, if of childbearing potential, they must be abstinent or have used adequate contraceptive precautions for 30 days prior to receiving the study vaccination and 84 days post-vaccine. sexually active male participants who are considered sexually fertile must agree to use a barrier method of contraception during sexual activity with a female of childbearing potential from the time of vaccination until at least 84 days after the vaccination. participants must provide written informed consent or their legal representative must understand and give written consent to the procedure. participants must be willing and able to comply with all the required study visits and follow-up required by this protocol, and be able to complete the diary card after vaccination or have a caregiver available to assist with these matters.

inclusion criteria: healthy adult male and female volunteers between 18 and 65 years of age, inclusive. participants who received a primary janssen ad26.cov2.s vaccine ≥ 60 days prior to receiving the study vaccine. body mass index within the range 18 - 32 kg/m2 both inclusive. participants who, judged by the investigator, are in stable health as determined by their pre-study medical history, physical examination, and clinical laboratory tests. female participants must be either of non-childbearing potential, i.e., surgically sterilized (defined as having undergone hysterectomy and/or bilateral oophorectomy and/or bilateral salpingectomy; tubal ligation alone is not considered sufficient) or one year postmenopausal; or, if of childbearing potential, they must be abstinent or have used adequate contraceptive precautions for 30 days prior to receiving the study vaccination and 84 days post-vaccine. sexually active male participants who are considered sexually fertile must agree to use a barrier method of contraception during sexual activity with a female of childbearing potential from the time of vaccination until at least 84 days after the vaccination. participants must provide written informed consent or their legal representative must understand and give written consent to the procedure. participants must be willing and able to comply with all the required study visits and follow-up required by this protocol, and be able to complete the diary card after vaccination or have a caregiver available to assist with these matters.