The purpose of this study is to demonstrate the non-inferiority of a heterologous prime-boost regimen using Ad26.ZEBOV as prime and MVA-BN-Filo as boost administered at different doses at a 56-day interval versus the same regimen with the recently released batches of Ad26.ZEBOV and MVA-BN-Filo in terms of humoral immune response against the Ebola virus (EBOV) GP (glycoprotein) as measured by enzyme-linked immunosorbent assay (ELISA) at 21 days post boost.

This is a randomized, double-blind, placebo-controlled, parallel-group, multicenter study to evaluate safety and immunogenicity of Ad26.ZEBOV and MVA-BN-Filo at different dose levels, administered to healthy adults participants. The study consists of a Screening period of up to 6 weeks, vaccinations on Day 1 and Day 57, and a post-vaccination phase until the 6 months post-boost visit (Day 237). The participants will be randomized at baseline (on Day 1) in a 2:2:2:1 ratio to Groups 1, 2, 3 and 4. Safety will be monitored throughout the study.

Inclusion criteria :

• Must be healthy in the Investigator's clinical judgment on the basis of medical history, physical examination, electrocardiogram (ECG) and vital signs performed at Screening
• Must be healthy on the basis of clinical laboratory tests performed at Screening
• Before randomization, a woman must be either of childbearing potential and practicing (or intending to practice) a highly effective method of birth control consistent with local regulations regarding the use of birth control methods for participants participating in clinical studies, beginning at least 28 days prior to vaccination OR not of childbearing potential: postmenopausal [greater than (>)] 45 years of age with amenorrhea for at least 2 years or any age with amenorrhea for at least 6 months, and a serum follicle stimulating hormone (FSH) level >40 international unit per milliliter (IU/L); permanently sterilized (for example, bilateral tubal occlusion [which includes tubal ligation procedures as consistent with local regulations], hysterectomy, bilateral salpingectomy, bilateral oophorectomy); or otherwise be incapable of pregnancy
• Woman of childbearing potential must have a negative serum [beta-human chorionic gonadotropin (beta-hCG)] at Screening and a negative urine beta-hCG pregnancy test immediately prior to each study vaccine administration
• Man who is sexually active with a woman of childbearing potential and has not had a vasectomy performed more than 1 year prior to Screening must be willing to use condoms for sexual intercourse beginning prior to enrollment, in addition to the birth control method used by the female partner

Exclusion criteria:

• Having received a candidate Ebola vaccine
• Diagnosed with Ebola virus disease, or prior exposure to Ebola virus, including travel to West Africa less than 1 month prior to Screening. West Africa includes but is not limited to the countries of Guinea, Liberia, Mali, and Sierra Leone
• Having received any experimental candidate adenovirus serotype 26 (vector: Ad26) or Modified Vaccinia Ankara (MVA)- based vaccine in the past
• Known allergy or history of anaphylaxis or other serious adverse reactions to vaccines or vaccine products (including any of the constituents of the study vaccines) including known allergy to egg, egg products and aminoglycosides
• Presence of acute illness or temperature greater than or equal to (>=) 38.0 (°C) centigrade on Day 1