* pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose * positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing * is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 * receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars * body mass index (bmi) \<18 or \>30 * current or history of the following medical conditions: 1. respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); 2. hypertension, resting systolic blood pressure \>150 mm hg or a diastolic blood pressure \>95 mm hg 3. malignancy within 5 years of screening 4. cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) 5. diabetes mellitus 6. use of immunoglobulin or blood products in last 6 months 7. history of severe allergic reaction or anaphylaxis after immunization * immunosuppression as a result of underlying illness or treatment including: 1. primary immunodeficiencies 2. long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) 3. current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) 4. history of solid organ or bone marrow transplantation 5. any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. * fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: 1. tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site 2. implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) 3. any metal implants or implantable medical device within the electroporation site * prisoners or subjects who are compulsorily detained (involuntary incarceration) * reported active drug or alcohol or substance abuse or dependence. * current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) * healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period * other condition deemed ineligible for the study at the discretion of investigator * employee of the study center directly involved with the proposed study or with study investigators * previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)

* pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose * positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing * is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 * receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars * body mass index (bmi) \<18 or \>30 * current or history of the following medical conditions: 1. respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); 2. hypertension, resting systolic blood pressure \>150 mm hg or a diastolic blood pressure \>95 mm hg 3. malignancy within 5 years of screening 4. cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) 5. diabetes mellitus 6. use of immunoglobulin or blood products in last 6 months 7. history of severe allergic reaction or anaphylaxis after immunization * immunosuppression as a result of underlying illness or treatment including: 1. primary immunodeficiencies 2. long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) 3. current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) 4. history of solid organ or bone marrow transplantation 5. any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. * fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: 1. tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site 2. implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) 3. any metal implants or implantable medical device within the electroporation site * prisoners or subjects who are compulsorily detained (involuntary incarceration) * reported active drug or alcohol or substance abuse or dependence. * current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) * healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period * other condition deemed ineligible for the study at the discretion of investigator * employee of the study center directly involved with the proposed study or with study investigators * previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)

pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars body mass index (bmi) <18 or >30 current or history of the following medical conditions: respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); hypertension, resting systolic blood pressure >150 mm hg or a diastolic blood pressure >95 mm hg malignancy within 5 years of screening cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) diabetes mellitus use of immunoglobulin or blood products in last 6 months history of severe allergic reaction or anaphylaxis after immunization immunosuppression as a result of underlying illness or treatment including: primary immunodeficiencies long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) history of solid organ or bone marrow transplantation any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) any metal implants or implantable medical device within the electroporation site prisoners or subjects who are compulsorily detained (involuntary incarceration) reported active drug or alcohol or substance abuse or dependence. current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period other condition deemed ineligible for the study at the discretion of investigator employee of the study center directly involved with the proposed study or with study investigators previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)

pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars body mass index (bmi) <18 or >30 current or history of the following medical conditions: respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); hypertension, resting systolic blood pressure >150 mm hg or a diastolic blood pressure >95 mm hg malignancy within 5 years of screening cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) diabetes mellitus use of immunoglobulin or blood products in last 6 months history of severe allergic reaction or anaphylaxis after immunization immunosuppression as a result of underlying illness or treatment including: primary immunodeficiencies long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) history of solid organ or bone marrow transplantation any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) any metal implants or implantable medical device within the electroporation site prisoners or subjects who are compulsorily detained (involuntary incarceration) reported active drug or alcohol or substance abuse or dependence. current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period other condition deemed ineligible for the study at the discretion of investigator employee of the study center directly involved with the proposed study or with study investigators previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)

- pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose - positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing - is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 - receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars - body mass index (bmi) <18 or >30 - current or history of the following medical conditions: 1. respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); 2. hypertension, resting systolic blood pressure >150 mm hg or a diastolic blood pressure >95 mm hg 3. malignancy within 5 years of screening 4. cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) 5. diabetes mellitus 6. use of immunoglobulin or blood products in last 6 months 7. history of severe allergic reaction or anaphylaxis after immunization - immunosuppression as a result of underlying illness or treatment including: 1. primary immunodeficiencies 2. long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) 3. current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) 4. history of solid organ or bone marrow transplantation 5. any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. - fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: 1. tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site 2. implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) 3. any metal implants or implantable medical device within the electroporation site - prisoners or subjects who are compulsorily detained (involuntary incarceration) - reported active drug or alcohol or substance abuse or dependence. - current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) - healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period - other condition deemed ineligible for the study at the discretion of investigator - employee of the study center directly involved with the proposed study or with study investigators - previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)

- pregnant or breastfeeding, or intending to become pregnant or father children within the projected duration of the trial starting with the screening visit until 3 months following last dose - positive serum pregnancy test during screening or positive urine pregnancy test prior to dosing - is currently participating in or has participated in a study with an investigational product within 6 months preceding day 0 - receipt of an investigational product for prophylaxis or treatment of covid-19, mers or sars - body mass index (bmi) <18 or >30 - current or history of the following medical conditions: 1. respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease); 2. hypertension, resting systolic blood pressure >150 mm hg or a diastolic blood pressure >95 mm hg 3. malignancy within 5 years of screening 4. cardiovascular diseases (e.g., myocardial infarction, congestive heart failure, cardiomyopathy or clinically significant arrhythmias) 5. diabetes mellitus 6. use of immunoglobulin or blood products in last 6 months 7. history of severe allergic reaction or anaphylaxis after immunization - immunosuppression as a result of underlying illness or treatment including: 1. primary immunodeficiencies 2. long term use (≥7 days) of oral or parenteral glucocorticoids at a dose of ≥20 mg/day of prednisone equivalent (use of inhaled, topical, nasal, otic, and ophthalmic corticosteroids are allowed) 3. current or anticipated during clinical trial use of disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate) and biologic disease modifying drugs such as tnf-α inhibitors (e.g., infliximab, adalimumab or etanercept) 4. history of solid organ or bone marrow transplantation 5. any prior history of other clinically significant immunosuppressive or clinically diagnosed autoimmune disease that may jeopardize the safety of the subject or require therapy that would interfere with study assessments or endpoint evaluation, or otherwise impact the validity of the study results. - fewer than two acceptable sites available for id injection and ep considering the deltoid and anterolateral quadriceps muscles. the following are unacceptable sites: 1. tattoos, keloids or hypertrophic scars located within 2 cm of intended administration site 2. implantable-cardioverter-defibrillator (icd) or pacemaker (to prevent a life-threatening arrhythmia) that is located ipsilateral to the deltoid injection site (unless deemed acceptable by a cardiologist) 3. any metal implants or implantable medical device within the electroporation site - prisoners or subjects who are compulsorily detained (involuntary incarceration) - reported active drug or alcohol or substance abuse or dependence. - current smoker or vaper (use of cigarette or e-cigarette at least once in last 30 days) - healthcare worker who may provide medical care to sars-cov-2 cases or occupationally in high risk for sars-cov-2 exposure during the study period - other condition deemed ineligible for the study at the discretion of investigator - employee of the study center directly involved with the proposed study or with study investigators - previously been laboratory-confirmed as sars-cov-2 infection or determined to be a close-contact of sars-cov-2 confirmed case by public health authorities (for part a only)