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

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 ill…