inclusion criteria: inclusion criteria 1. healthy adult men or women aged 18 to 55 years 2. full course of vaccination, including booster vaccination (i.e., having received 3 doses) with comirnaty, with the booster dose being administered at least 10 weeks before day 1 as documented in a respective vaccination certificate 3. able to understand the participant information and providing written informed consent 4. body mass index of 18.5 to 30.0 kg/m² and weight \> 50 kg at screening 5. women of childbearing potential must: 1. have a negative pregnancy test at screening (blood) and at day 1 (urine) 2. agree to use, and be able to comply with, highly effective measures of contraception without interruption, from 14 days before prime-2-cov_beta booster vaccination until the end of the study. a highly effective method of contraception or birth control (failure rate less than 1% per year when used consistently and correctly) for this study: combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal, injectable), progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, sexual abstinence or vasectomized sexual partner. abstinence is only acceptable as true abstinence when this is in line with the preferred and usual lifestyle of the participant (abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. (periodic abstinence \[e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal\] are not acceptable methods of contraception.) postmenopausal (no menses for at least 1 year without alternative medical cause) or surgically sterile women (tubal ligation, hysterectomy or bilateral oophorectomy) may be enrolled. 6. male participants must agree not to intend to father a child or to donate sperm starting at screening, throughout the clinical study. male participants must also 1. abstain from sexual intercourse with a female partner (acceptable only if it is the participant's usual form of birth control/lifestyle choice: abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant or 2. use adequate barrier contraception (male condom) during treatment with the investigational product until the end of the study, and 3. ensure that, if they have a female partner of childbearing potential, the partner uses a highly effective contraceptive method as outlined in inclusion criterion number 5 4. use condoms during the entire study if they have a pregnant partner, to avoid exposure of the fetus to the investigational product 7. willing and able to comply with all study procedures based on the investigator's judgment

inclusion criteria: inclusion criteria 1. healthy adult men or women aged 18 to 55 years 2. full course of vaccination, including booster vaccination (i.e., having received 3 doses) with comirnaty, with the booster dose being administered at least 10 weeks before day 1 as documented in a respective vaccination certificate 3. able to understand the participant information and providing written informed consent 4. body mass index of 18.5 to 30.0 kg/m² and weight \> 50 kg at screening 5. women of childbearing potential must: 1. have a negative pregnancy test at screening (blood) and at day 1 (urine) 2. agree to use, and be able to comply with, highly effective measures of contraception without interruption, from 14 days before prime-2-cov_beta booster vaccination until the end of the study. a highly effective method of contraception or birth control (failure rate less than 1% per year when used consistently and correctly) for this study: combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal, injectable), progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, sexual abstinence or vasectomized sexual partner. abstinence is only acceptable as true abstinence when this is in line with the preferred and usual lifestyle of the participant (abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. (periodic abstinence \[e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal\] are not acceptable methods of contraception.) postmenopausal (no menses for at least 1 year without alternative medical cause) or surgically sterile women (tubal ligation, hysterectomy or bilateral oophorectomy) may be enrolled. 6. male participants must agree not to intend to father a child or to donate sperm starting at screening, throughout the clinical study. male participants must also 1. abstain from sexual intercourse with a female partner (acceptable only if it is the participant's usual form of birth control/lifestyle choice: abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant or 2. use adequate barrier contraception (male condom) during treatment with the investigational product until the end of the study, and 3. ensure that, if they have a female partner of childbearing potential, the partner uses a highly effective contraceptive method as outlined in inclusion criterion number 5 4. use condoms during the entire study if they have a pregnant partner, to avoid exposure of the fetus to the investigational product 7. willing and able to comply with all study procedures based on the investigator's judgment

inclusion criteria: inclusion criteria healthy adult men or women aged 18 to 55 years full course of vaccination, including booster vaccination (i.e., having received 3 doses) with comirnaty, with the booster dose being administered at least 10 weeks before day 1 as documented in a respective vaccination certificate able to understand the participant information and providing written informed consent body mass index of 18.5 to 30.0 kg/m² and weight > 50 kg at screening women of childbearing potential must: have a negative pregnancy test at screening (blood) and at day 1 (urine) agree to use, and be able to comply with, highly effective measures of contraception without interruption, from 14 days before prime-2-cov_beta booster vaccination until the end of the study. a highly effective method of contraception or birth control (failure rate less than 1% per year when used consistently and correctly) for this study: combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal, injectable), progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, sexual abstinence or vasectomized sexual partner. abstinence is only acceptable as true abstinence when this is in line with the preferred and usual lifestyle of the participant (abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. (periodic abstinence [e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal] are not acceptable methods of contraception.) postmenopausal (no menses for at least 1 year without alternative medical cause) or surgically sterile women (tubal ligation, hysterectomy or bilateral oophorectomy) may be enrolled. male participants must agree not to intend to father a child or to donate sperm starting at screening, throughout the clinical study. male participants must also abstain from sexual intercourse with a female partner (acceptable only if it is the participant's usual form of birth control/lifestyle choice: abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant or use adequate barrier contraception (male condom) during treatment with the investigational product until the end of the study, and ensure that, if they have a female partner of childbearing potential, the partner uses a highly effective contraceptive method as outlined in inclusion criterion number 5 use condoms during the entire study if they have a pregnant partner, to avoid exposure of the fetus to the investigational product willing and able to comply with all study procedures based on the investigator's judgment

inclusion criteria: inclusion criteria healthy adult men or women aged 18 to 55 years full course of vaccination, including booster vaccination (i.e., having received 3 doses) with comirnaty, with the booster dose being administered at least 10 weeks before day 1 as documented in a respective vaccination certificate able to understand the participant information and providing written informed consent body mass index of 18.5 to 30.0 kg/m² and weight > 50 kg at screening women of childbearing potential must: have a negative pregnancy test at screening (blood) and at day 1 (urine) agree to use, and be able to comply with, highly effective measures of contraception without interruption, from 14 days before prime-2-cov_beta booster vaccination until the end of the study. a highly effective method of contraception or birth control (failure rate less than 1% per year when used consistently and correctly) for this study: combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal, injectable), progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, sexual abstinence or vasectomized sexual partner. abstinence is only acceptable as true abstinence when this is in line with the preferred and usual lifestyle of the participant (abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. (periodic abstinence [e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal] are not acceptable methods of contraception.) postmenopausal (no menses for at least 1 year without alternative medical cause) or surgically sterile women (tubal ligation, hysterectomy or bilateral oophorectomy) may be enrolled. male participants must agree not to intend to father a child or to donate sperm starting at screening, throughout the clinical study. male participants must also abstain from sexual intercourse with a female partner (acceptable only if it is the participant's usual form of birth control/lifestyle choice: abstinent on a long-term and persistent basis). the reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant or use adequate barrier contraception (male condom) during treatment with the investigational product until the end of the study, and ensure that, if they have a female partner of childbearing potential, the partner uses a highly effective contraceptive method as outlined in inclusion criterion number 5 use condoms during the entire study if they have a pregnant partner, to avoid exposure of the fetus to the investigational product willing and able to comply with all study procedures based on the investigator's judgment