* acute febrile illness with temperature \>100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; * positive sars-cov-2 pcr test, if results are available prior to dosing; * pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; * positive pregnancy test during screening or immediately prior to booster dose; * positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; * is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); * currently participating in another study with an investigational product during the conduct of this study; * previous or planned receipt of any covid-19 booster vaccine during the trial period * medical conditions as follows: * respiratory diseases * history of hypersensitivity or severe allergic reaction * uncontrolled hypertension * uncontrolled diabetes mellitus * malignancy within the past 2 years, with the exception of superficial skin * history of cardiovascular disease * history of myocarditis or pericarditis * history of seizures within the past 2 years * underlying immunosuppressive illness * lack of acceptable sites for id injection and ep * blood donation or transfusion within 1 month prior to day 0; * reported alcohol or substance abuse/dependence or illicit drug use within the past year; * any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.

* acute febrile illness with temperature \>100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; * positive sars-cov-2 pcr test, if results are available prior to dosing; * pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; * positive pregnancy test during screening or immediately prior to booster dose; * positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; * is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); * currently participating in another study with an investigational product during the conduct of this study; * previous or planned receipt of any covid-19 booster vaccine during the trial period * medical conditions as follows: * respiratory diseases * history of hypersensitivity or severe allergic reaction * uncontrolled hypertension * uncontrolled diabetes mellitus * malignancy within the past 2 years, with the exception of superficial skin * history of cardiovascular disease * history of myocarditis or pericarditis * history of seizures within the past 2 years * underlying immunosuppressive illness * lack of acceptable sites for id injection and ep * blood donation or transfusion within 1 month prior to day 0; * reported alcohol or substance abuse/dependence or illicit drug use within the past year; * any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.

acute febrile illness with temperature >100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; positive sars-cov-2 pcr test, if results are available prior to dosing; pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; positive pregnancy test during screening or immediately prior to booster dose; positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); currently participating in another study with an investigational product during the conduct of this study; previous or planned receipt of any covid-19 booster vaccine during the trial period medical conditions as follows: respiratory diseases history of hypersensitivity or severe allergic reaction uncontrolled hypertension uncontrolled diabetes mellitus malignancy within the past 2 years, with the exception of superficial skin history of cardiovascular disease history of myocarditis or pericarditis history of seizures within the past 2 years underlying immunosuppressive illness lack of acceptable sites for id injection and ep blood donation or transfusion within 1 month prior to day 0; reported alcohol or substance abuse/dependence or illicit drug use within the past year; any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.

acute febrile illness with temperature >100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; positive sars-cov-2 pcr test, if results are available prior to dosing; pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; positive pregnancy test during screening or immediately prior to booster dose; positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); currently participating in another study with an investigational product during the conduct of this study; previous or planned receipt of any covid-19 booster vaccine during the trial period medical conditions as follows: respiratory diseases history of hypersensitivity or severe allergic reaction uncontrolled hypertension uncontrolled diabetes mellitus malignancy within the past 2 years, with the exception of superficial skin history of cardiovascular disease history of myocarditis or pericarditis history of seizures within the past 2 years underlying immunosuppressive illness lack of acceptable sites for id injection and ep blood donation or transfusion within 1 month prior to day 0; reported alcohol or substance abuse/dependence or illicit drug use within the past year; any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.

acute febrile illness with temperature >100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; positive sars-cov-2 pcr test, if results are available prior to dosing; pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; positive pregnancy test during screening or immediately prior to booster dose; positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); currently participating in another study with an investigational product during the conduct of this study; previous or planned receipt of any covid-19 booster vaccine during the trial period medical conditions as follows: respiratory diseases history of hypersensitivity or severe allergic reaction uncontrolled hypertension uncontrolled diabetes mellitus malignancy within the past 2 years, with the exception of superficial skin history of cardiovascular history of seizures within the past 2 years underlying immunosuppressive illness lack of acceptable sites for id injection and ep blood donation or transfusion within 1 month prior to day 0; reported alcohol or substance abuse/dependence or illicit drug use within the past year; any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.

acute febrile illness with temperature >100.4°f (38.0°c) or acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of breath, sore throat) within the prior 72 hours; positive sars-cov-2 pcr test, if results are available prior to dosing; pregnant or breastfeeding, or intending to become pregnant or intending to father children within the projected duration of the study starting from the screening visit until day 28 post booster dose; positive pregnancy test during screening or immediately prior to booster dose; positive hiv rapid test, hepatitis b surface antigen (hbsag) or hepatitis c antibody at screening; is currently participating or has participated in a study with an ip within 30 days preceding day 0 (documented receipt of placebo in a previous study would be permissible for study eligibility); currently participating in another study with an investigational product during the conduct of this study; previous or planned receipt of any covid-19 booster vaccine during the trial period medical conditions as follows: respiratory diseases history of hypersensitivity or severe allergic reaction uncontrolled hypertension uncontrolled diabetes mellitus malignancy within the past 2 years, with the exception of superficial skin history of cardiovascular history of seizures within the past 2 years underlying immunosuppressive illness lack of acceptable sites for id injection and ep blood donation or transfusion within 1 month prior to day 0; reported alcohol or substance abuse/dependence or illicit drug use within the past year; any non-study vaccine (e.g., influenza vaccine) within 2 weeks prior to the dose of ip.