Evaluation of Safety, Tolerability and Immune Responses of Ebola-S and Marburg Vaccines in Healthy Adults

Inclusion Criteria: * Male or female participant must be between 18-50 (inclusive) years of age; * Meet criteria for plasma donation\*; * Available for clinic follow-up through Day 99 and one additional follow-up call on Day 181 (±14 days); * Agrees not to receive any vaccine from day of enrollment through Day 99; * Able to provide proof of identity to the satisfaction of the study clinician completing the enrollment process; * Agree to have photos taken of the vaccination site, if indicated ; * Willing to complete repeated plasmapheresis and other protocol requirements; * Must complete an Assessment of Understanding (AoU) by answering 9 out of 10 questions correctly at least once in 3 attempts; * Willing to donate blood for sample storage and future unspecified assay development; * Able to read (English) and willing to complete informed consent process; * In good general health without clinically significant medical history, based on medical history, physical examination, vital signs and clinical laboratory results; * Physical examination and laboratory results without clinically significant findings and a body mass index (BMI) ≥ 17 and ≤ 35 within the 28 days prior to vaccination; * Laboratory Criteria within 28 days prior to vaccination (normal per testing laboratory) for: complete blood count (CBC) with differential count, alanine aminotransferase (ALT), serum creatinine and total protein; * Serology screen negative for infectious diseases (hepatitis B, hepatitis C, HIV, HTLV (Human T-cell leukemia lymphoma virus), Chagas disease, Syphilis; * Nucleic acid test (NAT) negative for Human Immunodeficiency Virus (HIV), Hepatitis C Virus (HCV), Hepatitis B Virus (HBV), West Nile and Zika; * Negative antibody and reverse transcription polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome Covid 2 (SARS CoV-2) and free of current or prior symptoms concerning for COVID-19. Participants with a previous positive RT-PCR, at least 90 days prior to screening as reported in medical history, will not be excluded if they are antibody negative; * Female participant specific criteria: * Negative pregnancy serum test at screening and, negative urine pregnancy test before vaccination unless one of the following criteria is met: * At least 1 year post-menopausal; * Surgically sterile; * Use of oral, implantable, transdermal or injectable contraceptives for 21 days prior to and agrees to use through Day 181 ; * Use of another reliable form of contraception must be approved by the Investigator (e.g., double barrier method, Depo-Provera, intrauterine device, Norplant, oral contraceptives, contraceptive patches); * Male participants must agree: * Not to father a child or donate sperm through Day 181; * To use an effective means of birth control from at least 21 days prior to enrollment through Day 181 if assessed to be of reproductive potential. Meet the criteria described in the AABB (formerly known as American Association of Blood Bank) and Uniform Donor History Questionnaire, with the exception of travel for malaria or Variant Creutzfeldt-Jakob Disease (vCJD) risk Exclusion Criteria: * Investigational COVID-19, Ebola or Marburg vaccine in a prior clinical trial or prior receipt of a cAd3 adenoviral vectored investigational vaccine; * Use of immunomodulators and systemic glucocorticoids in daily doses of glucocorticoid equivalence \> 20 mg of prednisolone in the last 90 days and for periods exceeding 10 days. Non-steroidal anti-inflammatory drugs \[NSAIDS\] are permitted. Participants that have used less than the stated glucocorticoid dose may still be excluded at the Investigator's discretion; * Blood products within 112 days prior to enrollment; * Investigational research agents within 90 days prior to enrollment; * Any licensed vaccine, inclusive of "live-attenuated" vaccine (e.g., oral polio, yellow fever, measles, etc.), killed, or subunit vaccine, within 28 days prior to enrollment; * Any experimental vaccines within 6 months prior to enrollment; * Current anti-tuberculosis prophylaxis or therapy; * Female participant specific criteria: woman who is pregnant, breast-feeding or planning to become pregnant through Day 181 (±14 days); * Unsatisfactory vein assessment for plasmapheresis via peripheral access (more details in Section 5.2.1) * History of any of the following clinically significant conditions: * Serious adverse reactions to vaccines such as anaphylaxis, urticaria (hives), respiratory difficulty, angioedema, or abdominal pain; * Allergic reaction to excipients in the study vaccine including gentamycin, neomycin or streptomycin; * Clinically significant autoimmune disease or immunodeficiency; * Asthma that is not well controlled; * Positive result on a rapid plasma regain (RPR) test (A blood test for Syphilis); * Diabetes mellitus Type I or II; * Thyroid disease that is not well controlled ; * A history of hereditary angioedema (HAE), acquired angioedema (AAE), or idiopathic forms of angioedema; * Idiopathic urticaria within the last 1 year; * Hypertension that is not well controlled; * Bleeding disorder diagnosed by a doctor or use of anticoagulant medications such as, Coumadin, Eliquis, Pradaxa (e.g. factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or significant bruising or bleeding difficulties with IM injections or blood draws; * A malignancy that is active, currently being treated, or not surgically cured (breast or prostate cancer successfully treated, with or without surgery is excluded; if diagnosed malignancy is 5 or more years prior to enrollment and cured with no ongoing treatment it will NOT be considered an exclusion); * Seizure in the past 3 years or treatment for seizure disorder in the past 3 years; * Asplenia or functional asplenia; * Psychiatric condition that precludes compliance with the protocol; past or present psychoses; or within five years prior to enrollment, history of a suicide plan or attempt; * Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a participant's ability to give informed consent. * Abnormal laboratory results (per testing laboratory) * Positive COVID-19 symptom screen, SARS-CoV-2 RT-PCR, or SARS CoV-2 antibody test