Imvamune (licensed name of MVA being developed as a smallpox vaccine) has been tested in over 2,000 individuals and is on path for licensure. This study will be a Phase II to evaluate three different immunization schedules and two different modes of delivery. The study will look at condensed schedules. Study will randomize subjects to one of four arms.

This is a Phase II, randomized, open-label immunogenicity and safety study of different immunization schedules and delivery systems (syringe and needle vs. the Stratis™) in healthy, vaccinia-naïve adults 18 years to 40 years of age, inclusive. Approximately 352 subjects will be enrolled and randomized to one of four study arms. Study Arm A (N=88) will receive a two dose regimen of IMVAMUNE® (1x10^8 TCID50/0.5 mL per dose) via the SC route using a syringe and needle on Day 1 and 29. Study Arm B (N=88) will receive a two dose regimen of IMVAMUNE® (1x10^8 TCID50/0.5 mL per dose) via the SC route using a syringe and needle on Day 1 and 15. Study Arm C (N=88) will receive a two dose regimen of IMVAMUNE® (1x10^8 TCID50/0.5 mL) via the SC route using a syringe and needle on Day 1 and 22. Study Arm D (N=88) will receive a two dose regimen of IMVAMUNE® (1x10^8 TCID50/0.5 mL) via the SC route using the Stratis™ on Day 1 and 29. Immunogenicity assessments will be performed using ELISA and PRNT. Safety assessments will be done via solicited injection site and systemic reactions. Unsolicited AEs will be collected until 28 days post last injection and SAEs for the duration of the subjects' study participation. Safety laboratory assessments will be performed at baseline and 14 days after each vaccination. Primary outcome measures: For each subject, the peak PRNT will be defined as the highest titer among all available measurements post second vaccination; Occurrence of solicited local injection site reactions in subjects receiving vaccine via the Stratis™ compared to syringe and needle administration as collected on the memory aid and by in clinic assessment. Parent protocol to sub-study 13-0027.

Inclusion Criteria:

1. 18 to 40 years of age, inclusive.

2. Read, signed, and dated informed consent document.

3. Available for follow-up for the planned duration of the study (six months after last immunization).

4. Acceptable medical history by screening evaluation and limited physical assessment.

5. If the subject is female and of childbearing potential, negative serum or urine pregnancy test at screening and within 24 hours prior to vaccination.

6. If the subject is female and of childbearing potential*, she agrees to practice abstinence** or use acceptable contraception*** through 56 days after the last vaccination in order to avoid pregnancy:

   * a woman is considered of childbearing potential unless post-menopausal (>/= 1 year without menses) or surgically sterilized (tubal ligation, bilateral oophorectomy, or hysterectomy)

   **No sexual intercourse with men (vaginal penetration by a penis, coitus)

   ***Acceptable contraception methods are restricted to effective devices (IUDs, NuvaRing®) or licensed hormonal products with use of method for a minimum of 30 days prior to vaccination, condoms with spermicidal agents, monogamous relationship with a vasectomized partner who has been vasectomized for 6 months or more prior to study entry, or successful Essure placement with documented confirmation test at least 3 months after the procedure, and any other FDA-approved contraceptive method

7. Negative test for HIV.

8. Alanine Aminotransferase (ALT) <1.25 times the central lab upper limit of normal.

9. Negative hepatitis B surface antigen and negative antibody to hepatitis C virus.

10. Negative urine glucose and negative or trace urine protein by dipstick or urinalysis.

11. Adequate renal function (defined as a serum creatinine not exceeding the central lab's upper limit of normal).

12. Electrocardiogram (ECG) with no clinically significant abnormalities*

    * e.g., complete left or right bundle branch block, incomplete left bundle branch block or sustained ventricular arrhythmia, or two PVC's in a row, or ST elevation consistent with ischemia)

13. Acceptable hematology parameters:

    • Hemoglobin (Hgb) equal or above the lower limit of central lab normal (sex-specific);
    • White Blood Cell (WBC) > 3,800 and < 10,900/mm^3;
    • Platelets >/=120,000/mm^3

14. Body mass index >/=18.5-< 35.

15. Be able to understand and comply with planned study procedures.

Exclusion Criteria:

1. History of immunodeficiency.

2. Typical vaccinia scar.

3. Known or suspected history of smallpox vaccination including MVA alone or as a vector, as well as other investigational smallpox vaccines.

4. Military service prior to 1991 or after January 2003.

5. Known or suspected significant underlying illness including, but not limited to, clinically significant liver disease, diabetes mellitus, or moderate to severe kidney impairment.

6. Malignancy (not including squamous cell skin cancer or basal cell skin cancer unless at the vaccination site) or history of skin cancer at the vaccination site.

7. Active autoimmune disease. Persons with vitiligo or thyroid disease (e.g., taking thyroid hormone replacement) are not excluded.

8. History of myocardial infarction, angina, congestive heart failure, cardiomyopathy, stroke or transient ischemic attack, or other heart condition under the care of a doctor*

   *Subjects with a not clinically relevant heart murmur, i.e., without any pathological ECG/arrhythmias or under treatment are not excluded.

9. Systolic blood pressure >/= 150mmHg or diastolic blood pressure >/= 100mmHg.

10. Ten percent or greater risk of developing a myocardial infarction or coronary death within the next 10 years using the National Cholesterol Education Program's (NCEP) risk assessment tool*

    *NOTE that this criterion applies only to subjects 20 years of age and older AND only if at least one of the following apply:

    • have smoked a cigarette in the past month, and/or
    • have hypertension (defined as systolic blood pressure >140 mm Hg) or are on antihypertensive medication, and/or
    • have a family history of coronary heart disease in male first-degree relative (father or brother) <55 years of age or a female first-degree relative (mother or sister) <65 years of age

    URL for NCEP risk assessment tool: http://cvdrisk.nhlbi.nih.gov/calculator.asp (if a subject has an HDL of greater than 100mg/dl please enter 100 in the tool)

11. High-dose corticosteroid use for greater than 2 weeks duration within three months prior to vaccination or current use of immunosuppressive medication:

    • >5 mg prednisone or equivalent is considered high dose and immunosuppressive
    • Corticosteroid nasal sprays for allergic rhinitis are permissible
    • Persons who are using a topical steroid for mild uncomplicated dermatitis such as poison ivy or contact dermatitis may be enrolled the day after their therapy is completed
    • Inhaled steroids for asthma are not permissible
    • Oral/parenteral corticosteroids given for non-chronic conditions not expected to recur are permissible if the length of therapy was \

All participants are included in the baseline analysis population

Solicited events were collected for 15 days after each vaccination, unsolicited non-serious AEs through 28 days after last vaccination, and SAEs through 180 days after last vaccination.

Subjects were analyzed as treated for the safety population, so one subject randomized to Arm C but vaccinated out of window, equivalent to the schedule for Arm A, was analyzed as an Arm A subject.