Study Describing the Immunogenicity and Safety of Quadrivalent Recombinant Influenza Vaccine (RIV4) Versus a Licensed Quadrivalent-inactivated Influenza Vaccine (IIV4) (Fluarix® Quadrivalent) in Participants 18 Years of Age and Older in South Korea

* To describe the immune response induced by quadrivalent recombinant influenza vaccine (RIV4) and Quadrivalent-inactivated Influenza Vaccine (IIV4) in 18-49 and greater than or equal to (\>=) 50 years of age participants by hemagglutination inhibition (HAI) measurement method.
* To describe the safety profile of all participants in RIV4 and IIV4 groups.

The duration of each participant's participation was approximately 6 months.

Eligibility Criteria:
Inclusion Criteria:

* Aged \>=18 years on the day of inclusion.
* Participants who were overtly healthy as determined by medical evaluation including medical history, physical examination.
* Able to attend all scheduled visits and complied with all study procedures.
* Informed consent form was signed and dated.
* A female participant was eligible to participate if she was not pregnant or breastfeeding and one of the following conditions applies:

Was of non-childbearing potential. To be considered of non-childbearing potential, a female must be postmenopausal for at least 1 year, or surgically sterile OR Was of childbearing potential and agreed to use an effective contraceptive method or abstinence from at least 4 weeks prior to the study intervention administration until at least 4 weeks after study intervention administration.

A female participant of childbearing potential must had a negative highly sensitive pregnancy test (urine) before the first dose of study intervention.

Exclusion Criteria:

Participants were excluded from the study if any of the following criteria applied:

* Participation at the time of study enrollment, or in the 6 months preceding the study vaccination, or planned participation during the present study period in another clinical study investigating involving an Investigational Medical Product (IMP) (vaccine, drug), medical device, or medical procedure or in any other type of medical research.
* Receipt of any vaccine in the 4 weeks (28 days) preceding the study vaccination or planned receipt of any vaccine prior to Visit 2.
* Previous vaccination against influenza (in the preceding 6 months) with either the study vaccine or another vaccine.
* Receipt of immune globulins, blood, or blood-derived products in the past 3 months.
* Known or suspected abnormal immune function: immunosuppression, suspected congenital or acquired immunodeficiency based on medical history and physical examination, or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy, or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months).
* Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccines used in the study or to a vaccine containing any of the same substances.
* Thrombocytopenia or bleeding disorder, contraindicating IM vaccination based on the Investigator's judgment.
* Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily.
* Current alcohol abuse or drug addiction that in the opinion of the Investigator might interfere with the study conduct or completion.
* Chronic illness that, in the opinion of the Investigator, was at a stage where it might interfere with trial conduct or completion (Chronic illness may include, but is not limited to, cardiac disorders, renal disorders, auto-immune disorders, diabetes, psychiatric disorders, or chronic infection).
* Moderate or severe acute illness/infection (according to Investigator judgment) on the day of vaccination or febrile illness (temperature \>=38.0°C). A prospective participant should not be included in the study until the condition had resolved or the febrile event had subsided.
* Personal or family history of Guillain-Barré syndrome.
* Neoplastic disease or any hematologic malignancy (except localized skin or prostate cancer that was stable at the time of vaccination in the absence of therapy and participants who had a history of neoplastic disease and had been disease-free for \>= 5 years).
* Identified as an Investigator or employee of the Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (i.e., parent, spouse) of the Investigator or employee with direct involvement in the proposed study.

The above information was not intended to contain all considerations relevant to a potential participation in a clinical trial.