inclusion criteria: 1. capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol 2. participant must be able to comply with study procedures and be available for all study visits. 3. previously receive covid-19 vaccines either homologous or heterologous vaccination at least 3 doses and the last booster dose for more than 6 months prior to visit 2 (day 1). 4. be aged between 18 and 64 years, inclusive, at the time of signing informed consent 5. have a bmi between 18.5 and 35.0 kg/m2 inclusive 6. healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs 7. males must be surgically sterile (\> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination 8. females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of \<1% per year when used consistently and correctly), double-barrier contraceptive measures\* for at least 60 days following vaccination. * pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.

inclusion criteria: 1. capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol 2. participant must be able to comply with study procedures and be available for all study visits. 3. previously receive covid-19 vaccines either homologous or heterologous vaccination at least 3 doses and the last booster dose for more than 6 months prior to visit 2 (day 1). 4. be aged between 18 and 64 years, inclusive, at the time of signing informed consent 5. have a bmi between 18.5 and 35.0 kg/m2 inclusive 6. healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs 7. males must be surgically sterile (\> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination 8. females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of \<1% per year when used consistently and correctly), double-barrier contraceptive measures\* for at least 60 days following vaccination. * pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.

inclusion criteria: capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol participant must be able to comply with study procedures and be available for all study visits. previously receive covid-19 vaccines either homologous or heterologous vaccination at least 3 doses and the last booster dose for more than 6 months prior to visit 2 (day 1). be aged between 18 and 64 years, inclusive, at the time of signing informed consent have a bmi between 18.5 and 35.0 kg/m2 inclusive healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs males must be surgically sterile (> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of <1% per year when used consistently and correctly), double-barrier contraceptive measures* for at least 60 days following vaccination. pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.

inclusion criteria: capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol participant must be able to comply with study procedures and be available for all study visits. previously receive covid-19 vaccines either homologous or heterologous vaccination at least 3 doses and the last booster dose for more than 6 months prior to visit 2 (day 1). be aged between 18 and 64 years, inclusive, at the time of signing informed consent have a bmi between 18.5 and 35.0 kg/m2 inclusive healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs males must be surgically sterile (> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of <1% per year when used consistently and correctly), double-barrier contraceptive measures* for at least 60 days following vaccination. pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.

inclusion criteria: capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol participant must be able to comply with study procedures and be available for all study visits. have been fully vaccinated (primary vaccine 2 doses and 1 booster dose) with the astrazeneca vaccine or mrna vaccine more than 6 months prior to visit 2 (day 1) be aged between 18 and 64 years, inclusive, at the time of signing informed consent have a bmi between 18.5 and 35.0 kg/m2 inclusive healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs males must be surgically sterile (> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of <1% per year when used consistently and correctly), double-barrier contraceptive measures* for at least 60 days following vaccination. pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.

inclusion criteria: capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (icf) and in this protocol participant must be able to comply with study procedures and be available for all study visits. have been fully vaccinated (primary vaccine 2 doses and 1 booster dose) with the astrazeneca vaccine or mrna vaccine more than 6 months prior to visit 2 (day 1) be aged between 18 and 64 years, inclusive, at the time of signing informed consent have a bmi between 18.5 and 35.0 kg/m2 inclusive healthy as determined by the investigator based on pre-study medical history, physical examination and vital signs males must be surgically sterile (> 30 days since vasectomy with no viable sperm), practice true abstinence, or, if engaged in sexual activities with a female with childbearing potential, use condoms from the time of vaccination until 60 days after the vaccination females of childbearing potential must practice true abstinence, or, if engaged in sexual activities with a male, agree to use highly effective (failure rate of <1% per year when used consistently and correctly), double-barrier contraceptive measures* for at least 60 days following vaccination. pi to assess the suitability of contraceptive measures on a case-by-case basis. the measures can include: combined (estrogen and progestogen) hormonal contraception associated with inhibition of ovulation, progestogen-only hormonal contraception associated with inhibition of ovulation, intrauterine device, intrauterine hormone releasing system, and documented bilateral tubal occlusion hysterectomy, bilateral salpingectomy, bilateral essure® placement, and bilateral ovariectomy.