Please assess the completion status of the following clinical trial:

Trial Title: A Study to Evaluate a Range of Dose Levels and Vaccination Intervals of Ad26.COV2.S in Healthy Adults and Adolescents

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: DOUBLE
- Phase: PHASE2
- Number of Arms: 4.0

Eligibility Criteria:
Inclusion Criteria:~For Adults~* Participant must have a body mass index (BMI) less than (\<) 30.0 kilogram per meter square (kg/m\^2)~* Participant is 18 to 55 years of age, inclusive, or 65 years of age or older on the day of signing the informed consent form (ICF).~* Participant 18 to 55 years of age, inclusive: participant must be healthy, in the investigator's clinical judgment, as confirmed by medical history, physical examination, and vital signs performed at screening, and must not have comorbidities related to an increased risk of severe coronavirus disease-2019 (COVID-19), except for smoking and mild hypertension, which are allowed. Participant 65 years of age and older: In the investigator's clinical judgment, participant must be either in good or stable health. Participant may have underlying illnesses, as long as the symptoms and signs are medically controlled and not considered to be comorbidities related to an increased risk of severe COVID-19, except for smoking and mild hypertension, which are allowed. If on medication for a condition, the medication dose must have been stable for at least 12 weeks preceding vaccination and expected to remain stable for the duration of the study. Participant will be included on the basis of physical examination, medical history, and vital signs~* Participant will be included on the basis of physical examination, medical history, and vital signs~* All participants of childbearing potential must: a) Have a negative highly sensitive urine pregnancy test at screening, b)Have a negative highly sensitive urine pregnancy test immediately prior to each study vaccine administration~* Participant agrees to not donate bone marrow, blood, and blood products from the first study vaccine administration until 3 months after receiving the last dose of study vaccine~* Participant must be willing to provide verifiable identification, has means to be contacted and to contact the investigator during the study~For Adolescents:~* Participant is 12 to 17 years of age, inclusive, on the day of signing the informed consent form (ICF)~* Participants must have signed an ICF (or their legally acceptable representative or parent(s) \[preferably both parents if available or as per local requirements\] must sign) indicating that they understand the purpose of, and procedures required for, the study, are willing/able to adhere to the prohibitions and restrictions specified in the protocol and study procedures, and are willing (or the parents are willing for their adolescent) to participate in the study. Informed assent must be obtained from adolescents, depending on local regulations and practice~* Participant must be healthy, in the investigator's clinical judgment, as confirmed by medical history, physical examination, and vital signs performed at screening, and must not have comorbidities related to an increased risk of severe COVID-19~Exclusion Criteria:~For Adults~* Participant has a clinically significant acute illness (this does not include minor illnesses such as diarrhea or mild upper respiratory tract infection) or temperature greater than or equal to (\>=) 38.0 degree Celsius \[C\] (100.4 degree Fahrenheit \[F\]) within 24 hours prior to the planned first dose of study vaccine; randomization at a later date is permitted at the discretion of the investigator and after consultation with the sponsor~* Participant has a history of malignancy within 5 years before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, or malignancy, which is considered cured with minimal risk of recurrence)~* Participant has a known or suspected allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine)~* Participant received treatment with immunoglobulins in the 3 months or blood products in the 4 months before the planned administration of the first dose of study vaccine or has any plans to receive such treatment during the study~* Participant received an investigational drug (including investigational drugs for prophylaxis of COVID-19) or used an invasive investigational medical device within 30 days or received investigational Ig or monoclonal antibodies within 3 months, or received convalescent serum for COVID-19 treatment within 4 months or received an investigational vaccine (including investigational Adenoviral-vectored vaccines) within 6 months before the planned administration of the first dose of study vaccine or is currently enrolled or plans to participate in another investigational study during the course of this study For Adolescents~* Participant has a known or suspected allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine)~* Participants with a history of illness or with an ongoing illness that, in the opinion of the investigator, may pose additional risk to the participant if he/she participates in the study~* Participant has a history of Kawasaki disease~* Participant has a history of an underlying clinically significant acute or chronic medical condition or physical examination findings for which, in the opinion of the investigator, participation would not be in the best interest of the participant (example, compromise the well-being) or that could prevent, limit, or confound the protocol-specified assessments

- Gender: ALL
- Minimum Age: 12 Years
- Maximum Age: None
- Healthy Volunteers: t

Study Arms:
- Groups 1-6 (Type: EXPERIMENTAL): Participants will receive a 2-dose Ad26.COV2.S vaccination regimen at Days 1 and 57 at different dose levels (Groups 1-3), or a single-dose Ad26.COV2.S vaccination regimen at different dose levels (Groups 4-5), or placebo (Group 6). At unblinded phase, participants in Group 6 initially receiving placebo will be offered 2 doses of Ad26.COV2.S vaccine at a single dose level, at a 28-day interval. Participants will also receive a single antigen presentation injection with single dose level of Ad26.COV2.S at 4 months after second vaccination (Groups 1-5) or placebo (Group 6).
- Groups 7-8 (Type: EXPERIMENTAL): Participants will receive 2-dose Ad26.COV2.S vaccination regimen at Days 1 and 29 at fixed dose level (Groups 7) or placebo (Groups 8). At unblinded phase, participants in Group 8 initially receiving placebo will be offered 2 doses of Ad26.COV2.S vaccine at a single dose level, at a 28-day interval. Participants will also receive a single antigen presentation injection with single dose level of Ad26.COV2.S at 4 months after second vaccination (Group 7) or placebo (Group 8).
- Groups 9-10 (Type: EXPERIMENTAL): Participants will receive 2-dose Ad26.COV2.S vaccination regimen at Days 1 and 85 at fixed dose level (Group 9) or placebo (Group 10). At unblinded phase, participants in Group 10 initially receiving placebo will be offered 2 doses of Ad26.COV2.S vaccine at a single dose level, at a 28-day interval. Participants will also receive a single antigen presentation injection with single dose level of Ad26.COV2.S at 4 months after second vaccination (Group 9) or placebo (Group 10).
- Groups A-C (Type: EXPERIMENTAL): Participants will receive a single dose Ad26.COV2.S vaccination regimen at Day 1 at fixed dose level (Groups A and B) or placebo (Group C). At approximately 6 months of study participation (unblinded phase), participants in Group C initially receiving placebo will receive Ad26.COV2.S vaccine at a single dose level, at a 56-day interval.

Based on this trial design, predict the completion outcome and termination type (if applicable).