inclusion criteria: subjects must meet all inclusion criteria to be eligible for study participation. in addition, racial and ethnic minorities will be sought to obtain a diverse study population. subject has read, understood, and signed the informed consent form. healthy adult males and females 18 to 64 years of age, inclusive, at screening seronegative to sars-cov-2 and reverse transcription-polymerase chain reaction (rt-pcr)-negative at screening, without evidence of recent of exposure or viral respiratory disease not identified as influenza or rsv (febrile or lower respiratory tract infection) body mass index of ≥ 18 and ≤ 30 kg/m2 at screening must be in general good health before study participation with no clinically relevant abnormalities that could interfere with study assessments. women of childbearing potential (wocbp) and men whose sexual partners are wocbp must be able and willing to use at least 1 highly effective method of contraception (i.e., including hysterectomy, bilateral salpingectomy, and bilateral oophorectomy, hormonal oral [in combination with male condoms with spermicide], transdermal, implant, or injection, barrier [i.e., condom, diaphragm with spermicide]; intrauterine device; vasectomized partner [6 months minimum], clinically sterile partner; or abstinence) during the study. a female subject is considered a wocbp after menarche and until she is in a postmenopausal state for 12 consecutive months (without an alternative medical cause) or otherwise permanently sterile. subjects not of childbearing potential are not required to use any other forms of contraception during the study. non-childbearing potential is defined as subject confirmed: surgical sterilization (e.g., bilateral oophorectomy, bilateral salpingectomy, bilateral occlusion by cautery [essure system® is not acceptable], hysterectomy, or tubal ligation) postmenopausal (defined as permanent cessation of menstruation for at least 12 consecutive months prior to screening); if postmenopausal status is unclear, pregnancy tests will be performed prior to vaccinations. women of childbearing potential must have a negative pregnancy test before each vaccination. if menopausal status is unclear, a pregnancy test is required. must be able to attend all visits (scheduled and unscheduled, as applicable) for the duration of the study and comply with all study procedures, including daily completion of the diary card after each injection.

inclusion criteria: subjects must meet all inclusion criteria to be eligible for study participation. in addition, racial and ethnic minorities will be sought to obtain a diverse study population. subject has read, understood, and signed the informed consent form. healthy adult males and females 18 to 64 years of age, inclusive, at screening seronegative to sars-cov-2 and reverse transcription-polymerase chain reaction (rt-pcr)-negative at screening, without evidence of recent of exposure or viral respiratory disease not identified as influenza or rsv (febrile or lower respiratory tract infection) body mass index of ≥ 18 and ≤ 30 kg/m2 at screening must be in general good health before study participation with no clinically relevant abnormalities that could interfere with study assessments. women of childbearing potential (wocbp) and men whose sexual partners are wocbp must be able and willing to use at least 1 highly effective method of contraception (i.e., including hysterectomy, bilateral salpingectomy, and bilateral oophorectomy, hormonal oral [in combination with male condoms with spermicide], transdermal, implant, or injection, barrier [i.e., condom, diaphragm with spermicide]; intrauterine device; vasectomized partner [6 months minimum], clinically sterile partner; or abstinence) during the study. a female subject is considered a wocbp after menarche and until she is in a postmenopausal state for 12 consecutive months (without an alternative medical cause) or otherwise permanently sterile. subjects not of childbearing potential are not required to use any other forms of contraception during the study. non-childbearing potential is defined as subject confirmed: surgical sterilization (e.g., bilateral oophorectomy, bilateral salpingectomy, bilateral occlusion by cautery [essure system® is not acceptable], hysterectomy, or tubal ligation) postmenopausal (defined as permanent cessation of menstruation for at least 12 consecutive months prior to screening); if postmenopausal status is unclear, pregnancy tests will be performed prior to vaccinations. women of childbearing potential must have a negative pregnancy test before each vaccination. if menopausal status is unclear, a pregnancy test is required. must be able to attend all visits (scheduled and unscheduled, as applicable) for the duration of the study and comply with all study procedures, including daily completion of the diary card after each injection.

inclusion criteria: subjects must meet all inclusion criteria to be eligible for study participation. in addition, racial and ethnic minorities will be sought to obtain a diverse study population. 1. subject has read, understood, and signed the informed consent form. 2. healthy adult males and females 18 to 64 years of age, inclusive, at screening 3. seronegative to sars-cov-2 and reverse transcription-polymerase chain reaction (rt-pcr)-negative at screening, without evidence of recent of exposure or viral respiratory disease not identified as influenza or rsv (febrile or lower respiratory tract infection) 4. body mass index of ≥ 18 and ≤ 30 kg/m2 at screening 5. must be in general good health before study participation with no clinically relevant abnormalities that could interfere with study assessments. 6. women of childbearing potential (wocbp) and men whose sexual partners are wocbp must be able and willing to use at least 1 highly effective method of contraception (i.e., including hysterectomy, bilateral salpingectomy, and bilateral oophorectomy, hormonal oral [in combination with male condoms with spermicide], transdermal, implant, or injection, barrier [i.e., condom, diaphragm with spermicide]; intrauterine device; vasectomized partner [6 months minimum], clinically sterile partner; or abstinence) during the study. - a female subject is considered a wocbp after menarche and until she is in a postmenopausal state for 12 consecutive months (without an alternative medical cause) or otherwise permanently sterile. - subjects not of childbearing potential are not required to use any other forms of contraception during the study. non-childbearing potential is defined as subject confirmed: - surgical sterilization (e.g., bilateral oophorectomy, bilateral salpingectomy, bilateral occlusion by cautery [essure system® is not acceptable], hysterectomy, or tubal ligation) - postmenopausal (defined as permanent cessation of menstruation for at least 12 consecutive months prior to screening); if postmenopausal status is unclear, pregnancy tests will be performed prior to vaccinations. 7. women of childbearing potential must have a negative pregnancy test before each vaccination. if menopausal status is unclear, a pregnancy test is required. 8. must be able to attend all visits (scheduled and unscheduled, as applicable) for the duration of the study and comply with all study procedures, including daily completion of the diary card after each injection.

inclusion criteria: subjects must meet all inclusion criteria to be eligible for study participation. in addition, racial and ethnic minorities will be sought to obtain a diverse study population. 1. subject has read, understood, and signed the informed consent form. 2. healthy adult males and females 18 to 64 years of age, inclusive, at screening 3. seronegative to sars-cov-2 and reverse transcription-polymerase chain reaction (rt-pcr)-negative at screening, without evidence of recent of exposure or viral respiratory disease not identified as influenza or rsv (febrile or lower respiratory tract infection) 4. body mass index of ≥ 18 and ≤ 30 kg/m2 at screening 5. must be in general good health before study participation with no clinically relevant abnormalities that could interfere with study assessments. 6. women of childbearing potential (wocbp) and men whose sexual partners are wocbp must be able and willing to use at least 1 highly effective method of contraception (i.e., including hysterectomy, bilateral salpingectomy, and bilateral oophorectomy, hormonal oral [in combination with male condoms with spermicide], transdermal, implant, or injection, barrier [i.e., condom, diaphragm with spermicide]; intrauterine device; vasectomized partner [6 months minimum], clinically sterile partner; or abstinence) during the study. - a female subject is considered a wocbp after menarche and until she is in a postmenopausal state for 12 consecutive months (without an alternative medical cause) or otherwise permanently sterile. - subjects not of childbearing potential are not required to use any other forms of contraception during the study. non-childbearing potential is defined as subject confirmed: - surgical sterilization (e.g., bilateral oophorectomy, bilateral salpingectomy, bilateral occlusion by cautery [essure system® is not acceptable], hysterectomy, or tubal ligation) - postmenopausal (defined as permanent cessation of menstruation for at least 12 consecutive months prior to screening); if postmenopausal status is unclear, pregnancy tests will be performed prior to vaccinations. 7. women of childbearing potential must have a negative pregnancy test before each vaccination. if menopausal status is unclear, a pregnancy test is required. 8. must be able to attend all visits (scheduled and unscheduled, as applicable) for the duration of the study and comply with all study procedures, including daily completion of the diary card after each injection.