- has plans to become pregnant or is currently pregnant or breastfeeding. - seropositive to covid-19 by binding antibody titer assay. - confirmed positive for active infection of human immunodeficiency virus (hiv), hepatitis c virus (hcv), or presence of hepatitis b surface antigen (hbsag). - has known or suspected congenital or acquired immunodeficiency, or recent history or current use of immunosuppressive therapy. - history of organ and or stem cell transplantation. - has a history of malignancy other than squamous cell or basal cell skin cancer, unless there has been surgical excision that is considered to have achieved a cure. - has diabetes mellitus type 1 or type 2 (including cases controlled with diet alone) and/or thyroid disease. - has major psychiatric illness during the last 12 months that, in the physician investigator's opinion, would preclude participation. - has a history of other chronic diseases or conditions - has a current or history of substance abuse that, in the physician investigator's opinion, would preclude participation. - has tattoos, scars, or other marks that would, in the opinion of the physician investigator, interfere with the assessment of the injection site. - has a known allergy or history of anaphylaxis or other serious reaction to a vaccine, vaccine component, or latex. - had major surgery (per the physician investigator's judgment) in the month before screening or has plans to have major surgery during the study. - received blood products or immunoglobulin in the three months before screening or has plans to use during the study. - donated a unit of blood within eight weeks before study day 1 or has plans to donate blood during the study. - received an experimental covid-19 vaccine outside of this study or a covid-19 vaccine that has been given emergency use authorization from the fda - received live attenuated vaccine from 30 days before study day 1 until 30 days after the last study injection. - received killed or inactivated vaccine from 14 days before study day 1 and until 30 days after the last study injection. - received experimental therapeutic agents within three months before the first study injection or has plans to receive any experimental therapeutic agents during the entire course of the study. - concurrent participation in another study requiring blood draws or exposure to investigational or non-investigational vaccine/product (pharmaceutical or device) throughout the study period. - has an acute illness or temperature ≥38.0 degrees celsius (c)/100.4 degrees fahrenheit (f) on any study injection day or within 48 hours of planned study injection. - in the physician investigator's opinion, is unable to communicate reliably, is unlikely to adhere to study requirements, or has a condition that would limit completion of the study. - is unwilling to have their samples collected and stored for future research. - emergency medical services personnel and healthcare provider with patient contact in potentially high risk/high exposure settings as per screening physician's assessment. - current smoker or inhales vaporized nicotine "vaping" daily. current smoker is defined as an adult who has smoked 100 cigarettes in his or her lifetime and who currently smokes cigarettes.

- has plans to become pregnant or is currently pregnant or breastfeeding. - seropositive to covid-19 by binding antibody titer assay. - confirmed positive for active infection of human immunodeficiency virus (hiv), hepatitis c virus (hcv), or presence of hepatitis b surface antigen (hbsag). - has known or suspected congenital or acquired immunodeficiency, or recent history or current use of immunosuppressive therapy. - history of organ and or stem cell transplantation. - has a history of malignancy other than squamous cell or basal cell skin cancer, unless there has been surgical excision that is considered to have achieved a cure. - has diabetes mellitus type 1 or type 2 (including cases controlled with diet alone) and/or thyroid disease. - has major psychiatric illness during the last 12 months that, in the physician investigator's opinion, would preclude participation. - has a history of other chronic diseases or conditions - has a current or history of substance abuse that, in the physician investigator's opinion, would preclude participation. - has tattoos, scars, or other marks that would, in the opinion of the physician investigator, interfere with the assessment of the injection site. - has a known allergy or history of anaphylaxis or other serious reaction to a vaccine, vaccine component, or latex. - had major surgery (per the physician investigator's judgment) in the month before screening or has plans to have major surgery during the study. - received blood products or immunoglobulin in the three months before screening or has plans to use during the study. - donated a unit of blood within eight weeks before study day 1 or has plans to donate blood during the study. - received an experimental covid-19 vaccine outside of this study or a covid-19 vaccine that has been given emergency use authorization from the fda - received live attenuated vaccine from 30 days before study day 1 until 30 days after the last study injection. - received killed or inactivated vaccine from 14 days before study day 1 and until 30 days after the last study injection. - received experimental therapeutic agents within three months before the first study injection or has plans to receive any experimental therapeutic agents during the entire course of the study. - concurrent participation in another study requiring blood draws or exposure to investigational or non-investigational vaccine/product (pharmaceutical or device) throughout the study period. - has an acute illness or temperature ≥38.0 degrees celsius (c)/100.4 degrees fahrenheit (f) on any study injection day or within 48 hours of planned study injection. - in the physician investigator's opinion, is unable to communicate reliably, is unlikely to adhere to study requirements, or has a condition that would limit completion of the study. - is unwilling to have their samples collected and stored for future research. - emergency medical services personnel and healthcare provider with patient contact in potentially high risk/high exposure settings as per screening physician's assessment. - current smoker or inhales vaporized nicotine "vaping" daily. current smoker is defined as an adult who has smoked 100 cigarettes in his or her lifetime and who currently smokes cigarettes.