inclusion criteria: sars-cov-2 serology by akston (a quantitative anti-sars-cov-2 sp/rbd-specific igg elisa): * undetectable or \< 5 μg/ml titer and no known prior sars-cov-2 infection * body mass index (bmi) between 19.0 and 30.0 kg/m2, inclusive * general good health, without significant medical illness, as determined via physical exam findings, ecg or vital signs * note: one retest of vital functions and ecg is allowed within the screening window - no clinically significant laboratory abnormalities as determined by the investigator * note: one retest of lab tests is allowed within the screening window * informed consent form signed voluntarily before any study-related procedure is performed, indicating that the subject understands the purpose and procedures required for the study and is willing to participate in the study * willing to adhere to the prohibitions and restrictions specified in this protocol * non-smoker (including prior smokers having stopped smoking for more than 3 months at time of screening) or non-habitual smoker (habitual smokers are persons who smoke more than 4 cigarettes or other tobacco products on a weekly basis) and agree to not use tobacco products during confinement. * negative alcohol breath test and urine drug screen at screening and upon check-in at the clinical site. * negative hepatitis panel (including hepatitis b surface ag and anti-hepatitis c virus abs) and negative human immunodeficiency virus ab and ag screens at screening * female subjects should fulfil one of the following criteria: * at least 1 year post-menopausal (amenorrhea \>12 months and/or follicle stimulating hormone \>30 miu/ml) at screening; * surgically sterile (bilateral oophorectomy, hysterectomy, or tubal ligation); * will use adequate forms of contraceptives from screening to discharge. - female subjects of childbearing potential and male subjects who are sexually active with a female partner of childbearing potential must agree to the use of an effective method of birth control from screening to discharge * note: medically acceptable methods of contraception that may be used by the subject and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, double barrier, sterilization and vasectomy - female subject has a negative pregnancy test at screening and upon check-in at the clinical site. * note: pregnancy testing will consist of a serum pregnancy test at screening and urine pregnancy tests at other (dosing) visits, in all women.

inclusion criteria: sars-cov-2 serology by akston (a quantitative anti-sars-cov-2 sp/rbd-specific igg elisa): * undetectable or \< 5 μg/ml titer and no known prior sars-cov-2 infection * body mass index (bmi) between 19.0 and 30.0 kg/m2, inclusive * general good health, without significant medical illness, as determined via physical exam findings, ecg or vital signs * note: one retest of vital functions and ecg is allowed within the screening window - no clinically significant laboratory abnormalities as determined by the investigator * note: one retest of lab tests is allowed within the screening window * informed consent form signed voluntarily before any study-related procedure is performed, indicating that the subject understands the purpose and procedures required for the study and is willing to participate in the study * willing to adhere to the prohibitions and restrictions specified in this protocol * non-smoker (including prior smokers having stopped smoking for more than 3 months at time of screening) or non-habitual smoker (habitual smokers are persons who smoke more than 4 cigarettes or other tobacco products on a weekly basis) and agree to not use tobacco products during confinement. * negative alcohol breath test and urine drug screen at screening and upon check-in at the clinical site. * negative hepatitis panel (including hepatitis b surface ag and anti-hepatitis c virus abs) and negative human immunodeficiency virus ab and ag screens at screening * female subjects should fulfil one of the following criteria: * at least 1 year post-menopausal (amenorrhea \>12 months and/or follicle stimulating hormone \>30 miu/ml) at screening; * surgically sterile (bilateral oophorectomy, hysterectomy, or tubal ligation); * will use adequate forms of contraceptives from screening to discharge. - female subjects of childbearing potential and male subjects who are sexually active with a female partner of childbearing potential must agree to the use of an effective method of birth control from screening to discharge * note: medically acceptable methods of contraception that may be used by the subject and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, double barrier, sterilization and vasectomy - female subject has a negative pregnancy test at screening and upon check-in at the clinical site. * note: pregnancy testing will consist of a serum pregnancy test at screening and urine pregnancy tests at other (dosing) visits, in all women.

inclusion criteria: sars-cov-2 serology by akston (a quantitative anti-sars-cov-2 sp/rbd-specific igg elisa): - undetectable or < 5 μg/ml titer and no known prior sars-cov-2 infection - body mass index (bmi) between 19.0 and 30.0 kg/m2, inclusive - general good health, without significant medical illness, as determined via physical exam findings, ecg or vital signs - note: one retest of vital functions and ecg is allowed within the screening window - no clinically significant laboratory abnormalities as determined by the investigator - note: one retest of lab tests is allowed within the screening window - informed consent form signed voluntarily before any study-related procedure is performed, indicating that the subject understands the purpose and procedures required for the study and is willing to participate in the study - willing to adhere to the prohibitions and restrictions specified in this protocol - non-smoker (including prior smokers having stopped smoking for more than 3 months at time of screening) or non-habitual smoker (habitual smokers are persons who smoke more than 4 cigarettes or other tobacco products on a weekly basis) and agree to not use tobacco products during confinement. - negative alcohol breath test and urine drug screen at screening and upon check-in at the clinical site. - negative hepatitis panel (including hepatitis b surface ag and anti-hepatitis c virus abs) and negative human immunodeficiency virus ab and ag screens at screening - female subjects should fulfil one of the following criteria: - at least 1 year post-menopausal (amenorrhea >12 months and/or follicle stimulating hormone >30 miu/ml) at screening; - surgically sterile (bilateral oophorectomy, hysterectomy, or tubal ligation); - will use adequate forms of contraceptives from screening to discharge. - female subjects of childbearing potential and male subjects who are sexually active with a female partner of childbearing potential must agree to the use of an effective method of birth control from screening to discharge - note: medically acceptable methods of contraception that may be used by the subject and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, double barrier, sterilization and vasectomy - female subject has a negative pregnancy test at screening and upon check-in at the clinical site. - note: pregnancy testing will consist of a serum pregnancy test at screening and urine pregnancy tests at other (dosing) visits, in all women.

inclusion criteria: sars-cov-2 serology by akston (a quantitative anti-sars-cov-2 sp/rbd-specific igg elisa): - undetectable or < 5 μg/ml titer and no known prior sars-cov-2 infection - body mass index (bmi) between 19.0 and 30.0 kg/m2, inclusive - general good health, without significant medical illness, as determined via physical exam findings, ecg or vital signs - note: one retest of vital functions and ecg is allowed within the screening window - no clinically significant laboratory abnormalities as determined by the investigator - note: one retest of lab tests is allowed within the screening window - informed consent form signed voluntarily before any study-related procedure is performed, indicating that the subject understands the purpose and procedures required for the study and is willing to participate in the study - willing to adhere to the prohibitions and restrictions specified in this protocol - non-smoker (including prior smokers having stopped smoking for more than 3 months at time of screening) or non-habitual smoker (habitual smokers are persons who smoke more than 4 cigarettes or other tobacco products on a weekly basis) and agree to not use tobacco products during confinement. - negative alcohol breath test and urine drug screen at screening and upon check-in at the clinical site. - negative hepatitis panel (including hepatitis b surface ag and anti-hepatitis c virus abs) and negative human immunodeficiency virus ab and ag screens at screening - female subjects should fulfil one of the following criteria: - at least 1 year post-menopausal (amenorrhea >12 months and/or follicle stimulating hormone >30 miu/ml) at screening; - surgically sterile (bilateral oophorectomy, hysterectomy, or tubal ligation); - will use adequate forms of contraceptives from screening to discharge. - female subjects of childbearing potential and male subjects who are sexually active with a female partner of childbearing potential must agree to the use of an effective method of birth control from screening to discharge - note: medically acceptable methods of contraception that may be used by the subject and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, double barrier, sterilization and vasectomy - female subject has a negative pregnancy test at screening and upon check-in at the clinical site. - note: pregnancy testing will consist of a serum pregnancy test at screening and urine pregnancy tests at other (dosing) visits, in all women.