A Study of Ad26.COV2.S and Influenza Vaccines in Healthy Adults

The purpose of this study is to demonstrate the non-inferiority (NI) of the humoral immune response of the 4 influenza vaccine strains after concomitant administration of the Ad26.COV2.S vaccine and a seasonal quadrivalent standard-dose influenza vaccine versus the administration of a seasonal quadrivalent standard-dose influenza vaccine administered alone; and to demonstrate the NI of the binding antibody response after concomitant administration of Ad26.COV2.S vaccine and a seasonal quadrivalent standard-dose influenza vaccine versus the administration of Ad26.COV2.S vaccine administered alone.

Severe acute respiratory syndrome coronavirus(-2) (SARS CoV-2) is a highly transmissible and pathogenic coronavirus that has spread rapidly and globally and Influenza is a worldwide public health problem, responsible for significant morbidity and mortality. Ad26.COV2.S (also known as VAC31518, JNJ-78436735) is a monovalent vaccine composed of a recombinant, replication-incompetent human adenovirus type 26 (Ad26) vector, constructed to encode SARS-CoV-2 spike (S) protein, stabilized in its prefusion conformation. The seasonal influenza vaccines to be used in this study are quadrivalent (standard dose) and quadrivalent (high-dose) or equivalent formulated. The aim is to demonstrate the concomitant administration of the Ad26.COV2.S vaccine and a seasonal quadrivalent influenza vaccine (standard-dose) is non-inferior than the administration of either seasonal quadrivalent influenza vaccine (standard-dose) alone as measured by HI titers against each of the 4 influenza vaccine strains at 28 days after the administration of a quadrivalent seasonal influenza vaccine or Ad26.COV2.S vaccine alone as measured by Spiked-Enzyme-linked Immunosorbent Assay (S-ELISA) antibody titers at 28 days after the administration of the Ad26.COV2.S vaccine. This study consists of 3 phases: screening phase (Day -28 to 1), treatment phase (vaccination visits on Days 1 and 29), and a follow-up phase (28 days after each vaccination). Some of safety assessments will include physical examination, vital signs, clinical safety laboratory assessments, pregnancy testing, monitoring of adverse events (AEs), serious adverse events (SAEs), and adverse events of special interest (AESI). The total duration of the study is up to 7-8 months.

Note: The Informed Consent Form dated 25-Mar-2022 is final version of the study MASTER ICF, used by local countries to prepare the local language version of the ICF, which have been approved by the Ethics Committees. And the highlighted text in the ICF document are the guidance for country specific adaptation.

Eligibility Criteria:
Inclusion Criteria:

* Participant must be healthy, in the investigator's clinical judgment, as confirmed by medical history, physical examination, and vital signs performed at screening. Participants may have underlying illnesses, as long as the symptoms and signs are medically controlled
* Participant either received complete primary vaccination with an authorized/licensed coronavirus disease-2019 (COVID-19) vaccine (completed greater than or equal to \[\>=\] 6 months prior to the last vaccination received against COVID-19) or is COVID-19 vaccine-naive
* All participants who were born female and are of childbearing potential must: a. Have a negative highly sensitive urine pregnancy test at screening, b. Have a negative highly sensitive urine pregnancy test on the day of vaccination prior to each study vaccine administration
* Participant agrees to not donate or receive bone marrow, blood, and blood products from the administration of the study vaccine until 3 months after receiving the study vaccines
* Participant must be willing to provide verifiable identification to be contacted and to contact the investigator during the study

Exclusion Criteria:

* Participant has a history of malignancy within 1 year before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, or malignancies considered cured with minimal risk of recurrence per investigator's clinical judgment)
* Participant has a clinically significant acute illness (this does not include minor illnesses such as diarrhea or mild upper respiratory tract infection) or temperature \>= 38.0 degrees celsius (ºC) (100.4 degrees fahrenheit \[°F\]) within 24 hours prior to the planned dose of study vaccine; randomization at a later date is permitted at the discretion of the investigator
* Participant has history of thrombosis with thrombocytopenia syndrome (TTS) or heparin-induced thrombocytopenia and thrombosis (HITT)
* Participant has history of capillary leak syndrome
* Participant received a licensed/registered severe acute respiratory syndrome coronavirus(-2) (SARS-CoV-2) vaccine less than 6 months prior to first study vaccination (other than study vaccination)
* Participant has a history of any neurological disorders or seizures including Guillain-Barre syndrome, with the exception of febrile seizures during childhood