part 1 inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: 1. adults ≥ 18 and ≤ 64 years of age at screening. 2. willing and able to give informed consent prior to study enrollment and to comply with study procedures. 3. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile \[ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy\] or postmenopausal \[defined as amenorrhea ≥ 12 consecutive months\]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to and through the end of the study. 4. is medically stable, as determined by the investigator (based on a review of health status, vital signs \[to include body temperature\], medical history, and targeted physical examination \[to include body weight\]). vital signs must be within medically acceptable ranges prior to the vaccination. 5. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. 6. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to study vaccination or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the study vaccination.

part 1 inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: 1. adults ≥ 18 and ≤ 64 years of age at screening. 2. willing and able to give informed consent prior to study enrollment and to comply with study procedures. 3. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile \[ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy\] or postmenopausal \[defined as amenorrhea ≥ 12 consecutive months\]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to and through the end of the study. 4. is medically stable, as determined by the investigator (based on a review of health status, vital signs \[to include body temperature\], medical history, and targeted physical examination \[to include body weight\]). vital signs must be within medically acceptable ranges prior to the vaccination. 5. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. 6. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to study vaccination or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the study vaccination.

inclusion criteria: part 1 to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to and through the end of the study. is medically stable, as determined by the investigator (based on a review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to study vaccination or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the study vaccination.

inclusion criteria: part 1 to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to and through the end of the study. is medically stable, as determined by the investigator (based on a review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to study vaccination or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the study vaccination.

inclusion criteria: part 1 to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in-country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle. is medically stable, as determined by the investigator (based on review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. have previously received ≥ 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the first study booster.

inclusion criteria: part 1 to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in-country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle. is medically stable, as determined by the investigator (based on review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. have previously received ≥ 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in-country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle note: periodic abstinence (eg, calendar, ovulation, sympto-thermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. is medically stable, as determined by the investigator (based on review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received ≥ 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥ 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in-country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle note: periodic abstinence (eg, calendar, ovulation, sympto-thermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. is medically stable, as determined by the investigator (based on review of health status, vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received ≥ 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to the first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle note: periodic abstinence (eg, calendar, ovulation, sympto-thermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. is medically stable, as determined by the investigator (based on review of health status,vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to first study booster or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. condoms (male or female) with spermicide (if acceptable in country) diaphragm with spermicide cervical cap with spermicide intrauterine device oral or patch contraceptives norplant®, depo-provera®, or other in country regulatory approved contraceptive method that is designed to protect against pregnancy abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle note: periodic abstinence (eg, calendar, ovulation, sympto-thermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. is medically stable, as determined by the investigator (based on review of health status,vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received 2 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to first study booster or 3 doses of the moderna and/or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. is medically stable, as determined by the investigator (based on review of health status,vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received 2 homologous doses of either the moderna or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to first study booster or 3 homologous doses of either the moderna or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to first study booster.

inclusion criteria: to be included in this study, each individual must satisfy all the following criteria: adults ≥ 18 and ≤ 64 years of age at screening. willing and able to give informed consent prior to study enrollment and to comply with study procedures. female participants of childbearing potential (defined as any participant who has experienced menarche and who is not surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea ≥12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of the study or agree to consistently use a medically acceptable method of contraception listed below from ≥ 28 days prior to enrollment and through the end of the study. is medically stable, as determined by the investigator (based on review of health status,vital signs [to include body temperature], medical history, and targeted physical examination [to include body weight]). vital signs must be within medically acceptable ranges prior to the first vaccination. agrees to not participate in any other sars-cov-2 prevention or treatment trials for the duration of the study. note: for participants who become hospitalized with covid-19, participation in investigational treatment studies is permitted. have previously received 2 homologous doses of either the moderna or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 180 days prior to first study booster or 3 homologous doses of either the moderna or pfizer-biontech covid-19 prototype vaccines with the last dose having been given ≥ 90 days previously prior to first study booster.