inclusion criteria: subjects must meet all the following criteria to be considered eligible for the study: 1. male or female, ≥ 18 years old at day 0. 2. participant must provide consent indicating that she or he understands the purpose and potential risks and is willing and able to participate in the study and comply with all the study requirements and procedures (scheduled visits, laboratory tests, complete diaries, etc). 3. participant who has been vaccinated with two doses of vaxzevria at least 91 days before day 0 and a maximum of 365 days of the second dose. 4. has a negative rapid antigen test (rat) at day 0 5. participants may have underlying illnesses if are stable and well-controlled according to the investigator judgment. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 3 months prior to screening and for which neither a significant change in treatment or hospitalization for worsening is expected in the near future. 6. participant agrees not to donate blood, blood products and bone marrow at least 12 weeks before and after vaccination. 7. contraceptive use should be consistent with local regulation for participants in clinical trials. 1. female participants of childbearing potential \[defined as any female who has experienced menarche and until becoming postmenopausal\* (defined as having ≥ 12 months amenorrhea prior to screening without an alternative cause) unless is surgically sterile\]: i. have a negative pregnancy test on the day of vaccination. ii. use of any acceptable contraceptive method that should be started at screening and until 8 weeks after vaccination except hormonal contraception. acceptable contraceptive methods are: 1. hormonal contraception (progestogen-only or combined): oral, injectable or transdermal (patch) at least 30 days before day 0 and until 8 weeks after vaccination. 2. intrauterine device. 3. vasectomized partner (the vasectomized partner should be the sole partner for that participant). 4. sexual abstinence \*\*, as a form of contraception, is acceptable if in line with the participant's lifestyle. 5. condom b. male participants: i. vasectomized participants. ii. refrain from donating sperm for at least 28 days after day 0. iii. agree to use a male condom may be considered in women of childbearing potential partners, from screening and for at least 28 days after day 0. iv. sexual abstinence\*\*, as a form of contraception, is acceptable if in line with the participant's lifestyle. \* a high follicle stimulating hormone (fsh) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy. \*\* sexual abstinence is considered an effective method only if defined as refraining from heterosexual intercourse from screening until 8 weeks after receiving the vaccine for female participants and from screening until 4 weeks for male participants. periodic abstinence (e.g., calendar, ovulation) and withdrawal are not acceptable methods of contraception.

inclusion criteria: subjects must meet all the following criteria to be considered eligible for the study: 1. male or female, ≥ 18 years old at day 0. 2. participant must provide consent indicating that she or he understands the purpose and potential risks and is willing and able to participate in the study and comply with all the study requirements and procedures (scheduled visits, laboratory tests, complete diaries, etc). 3. participant who has been vaccinated with two doses of vaxzevria at least 91 days before day 0 and a maximum of 365 days of the second dose. 4. has a negative rapid antigen test (rat) at day 0 5. participants may have underlying illnesses if are stable and well-controlled according to the investigator judgment. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 3 months prior to screening and for which neither a significant change in treatment or hospitalization for worsening is expected in the near future. 6. participant agrees not to donate blood, blood products and bone marrow at least 12 weeks before and after vaccination. 7. contraceptive use should be consistent with local regulation for participants in clinical trials. 1. female participants of childbearing potential \[defined as any female who has experienced menarche and until becoming postmenopausal\* (defined as having ≥ 12 months amenorrhea prior to screening without an alternative cause) unless is surgically sterile\]: i. have a negative pregnancy test on the day of vaccination. ii. use of any acceptable contraceptive method that should be started at screening and until 8 weeks after vaccination except hormonal contraception. acceptable contraceptive methods are: 1. hormonal contraception (progestogen-only or combined): oral, injectable or transdermal (patch) at least 30 days before day 0 and until 8 weeks after vaccination. 2. intrauterine device. 3. vasectomized partner (the vasectomized partner should be the sole partner for that participant). 4. sexual abstinence \*\*, as a form of contraception, is acceptable if in line with the participant's lifestyle. 5. condom b. male participants: i. vasectomized participants. ii. refrain from donating sperm for at least 28 days after day 0. iii. agree to use a male condom may be considered in women of childbearing potential partners, from screening and for at least 28 days after day 0. iv. sexual abstinence\*\*, as a form of contraception, is acceptable if in line with the participant's lifestyle. \* a high follicle stimulating hormone (fsh) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy. \*\* sexual abstinence is considered an effective method only if defined as refraining from heterosexual intercourse from screening until 8 weeks after receiving the vaccine for female participants and from screening until 4 weeks for male participants. periodic abstinence (e.g., calendar, ovulation) and withdrawal are not acceptable methods of contraception.

inclusion criteria: subjects must meet all the following criteria to be considered eligible for the study: male or female, ≥ 18 years old at day 0. participant must provide consent indicating that she or he understands the purpose and potential risks and is willing and able to participate in the study and comply with all the study requirements and procedures (scheduled visits, laboratory tests, complete diaries, etc). participant who has been vaccinated with two doses of vaxzevria at least 91 days before day 0 and a maximum of 365 days of the second dose. has a negative rapid antigen test (rat) at day 0 participants may have underlying illnesses if are stable and well-controlled according to the investigator judgment. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 3 months prior to screening and for which neither a significant change in treatment or hospitalization for worsening is expected in the near future. participant agrees not to donate blood, blood products and bone marrow at least 12 weeks before and after vaccination. contraceptive use should be consistent with local regulation for participants in clinical trials. female participants of childbearing potential [defined as any female who has experienced menarche and until becoming postmenopausal* (defined as having ≥ 12 months amenorrhea prior to screening without an alternative cause) unless is surgically sterile]: i. have a negative pregnancy test on the day of vaccination. ii. use of any acceptable contraceptive method that should be started at screening and until 8 weeks after vaccination except hormonal contraception. acceptable contraceptive methods are: 1. hormonal contraception (progestogen-only or combined): oral, injectable or transdermal (patch) at least 30 days before day 0 and until 8 weeks after vaccination. 2. intrauterine device. 3. vasectomized partner (the vasectomized partner should be the sole partner for that participant). 4. sexual abstinence **, as a form of contraception, is acceptable if in line with the participant's lifestyle. 5. condom b. male participants: i. vasectomized participants. ii. refrain from donating sperm for at least 28 days after day 0. iii. agree to use a male condom may be considered in women of childbearing potential partners, from screening and for at least 28 days after day 0. iv. sexual abstinence**, as a form of contraception, is acceptable if in line with the participant's lifestyle. * a high follicle stimulating hormone (fsh) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy. ** sexual abstinence is considered an effective method only if defined as refraining from heterosexual intercourse from screening until 8 weeks after receiving the vaccine for female participants and from screening until 4 weeks for male participants. periodic abstinence (e.g., calendar, ovulation) and withdrawal are not acceptable methods of contraception.

inclusion criteria: subjects must meet all the following criteria to be considered eligible for the study: male or female, ≥ 18 years old at day 0. participant must provide consent indicating that she or he understands the purpose and potential risks and is willing and able to participate in the study and comply with all the study requirements and procedures (scheduled visits, laboratory tests, complete diaries, etc). participant who has been vaccinated with two doses of vaxzevria at least 91 days before day 0 and a maximum of 365 days of the second dose. has a negative rapid antigen test (rat) at day 0 participants may have underlying illnesses if are stable and well-controlled according to the investigator judgment. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 3 months prior to screening and for which neither a significant change in treatment or hospitalization for worsening is expected in the near future. participant agrees not to donate blood, blood products and bone marrow at least 12 weeks before and after vaccination. contraceptive use should be consistent with local regulation for participants in clinical trials. female participants of childbearing potential [defined as any female who has experienced menarche and until becoming postmenopausal* (defined as having ≥ 12 months amenorrhea prior to screening without an alternative cause) unless is surgically sterile]: i. have a negative pregnancy test on the day of vaccination. ii. use of any acceptable contraceptive method that should be started at screening and until 8 weeks after vaccination except hormonal contraception. acceptable contraceptive methods are: 1. hormonal contraception (progestogen-only or combined): oral, injectable or transdermal (patch) at least 30 days before day 0 and until 8 weeks after vaccination. 2. intrauterine device. 3. vasectomized partner (the vasectomized partner should be the sole partner for that participant). 4. sexual abstinence **, as a form of contraception, is acceptable if in line with the participant's lifestyle. 5. condom b. male participants: i. vasectomized participants. ii. refrain from donating sperm for at least 28 days after day 0. iii. agree to use a male condom may be considered in women of childbearing potential partners, from screening and for at least 28 days after day 0. iv. sexual abstinence**, as a form of contraception, is acceptable if in line with the participant's lifestyle. * a high follicle stimulating hormone (fsh) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy. ** sexual abstinence is considered an effective method only if defined as refraining from heterosexual intercourse from screening until 8 weeks after receiving the vaccine for female participants and from screening until 4 weeks for male participants. periodic abstinence (e.g., calendar, ovulation) and withdrawal are not acceptable methods of contraception.