The primary objective of the study was to provide sera (collected from participants before vaccination [Blood Sample 1] and after final vaccination [Blood Sample 2]) to the Center for Biologics Evaluation and Research (CBER) for further analysis by the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA) to support formulation recommendations for subsequent influenza vaccines.

All participants received 1 intramuscular injection of the study vaccine associated with their assigned group at Visit 1. For participants 6 months to < 9 years of age for whom 2 doses of influenza vaccine are recommended per Advisory Committee on Immunization Practices (ACIP) guidance, a second intramuscular injection of Fluzone Quadrivalent vaccine was administered at Visit 2 (28 days after Visit 1).

Blood specimens were obtained from all participants prior to the first vaccination:

• At Visit 1 (Day 0) and 28 days following the final vaccination (Visit 2, if no study vaccine was administered at Visit 2; or Visit 3, if a second dose of study vaccine was administered at Visit 2), for participants 6 months to < 9 years of age (Group 1 and Group 2)
• At Visit 1 and 21 (window, 21-28) days post-vaccination (Visit 2), for participants greater than or equal to (>=) 65 years of age (Group 3) Serious Adverse Events (SAEs), suspected unexpected serious adverse reactions (SUSARs), or Adverse Event of Special Interests (AESIs) were collected from Visit 1 through Visit 2 for participants receiving 1 dose of study vaccine, and from Visit 1 through Visit 3 for participants receiving 2 doses of study vaccine.

Study duration per participant was approximately 28 days for participants 6 months to less than (<) 9 years of age, and 21 days for participants >= 65 years of age.

Inclusion criteria :

An individual who fulfilled all of the following criteria were eligible for study enrollment:

• Aged 6 months to < 9 years or >= 65 years of age on the day of first study vaccination (study product administration).
• For participants 6 to < 12 months of age, born at full term of pregnancy (>= 37 weeks) and with a birth weight >= 5.5 pounds (2.5 kilograms).
• Informed consent form (ICF) had been signed and dated by participants >= 65 years of age.
• Assent form had been signed and dated by participants 7 to < 9 years of age, and ICF had been signed and dated by parent(s) or guardian(s) for participants 6 months to < 9 years of age.
• Participant and parent/guardian (of participants 6 months to < 9 years of age) were able to attend all scheduled visits and complied with all study procedures.

Exclusion criteria:

An individual who fulfilled any of the following criteria were excluded from study enrollment:

• Participation at the time of study enrollment (or in the 30 days preceding the first study vaccination) or planned participation during the present study period in another clinical study investigating a vaccine, drug, medical device, or medical procedure.
• Receipt of any vaccine in the 30 days preceding the first study vaccination, or planned receipt of any vaccine before Visit 2 for participants receiving 1 dose of influenza vaccine or Visit 3 for participants receiving 2 doses of influenza vaccine.
• Previous vaccination against influenza (in the 2019-2020 influenza season) with either study vaccine or another vaccine.
• Receipt of immune globulins, blood, or blood-derived products in the 3 months preceding planned inclusion.
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the 6 months preceding planned inclusion; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the 3 months preceding planned inclusion).
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to study vaccine or to a vaccine containing any of the same substances.
• Thrombocytopenia, which might be a contraindication for intramuscular vaccination, at the discretion of the Investigator.
• Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular vaccination.
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily.
• Current alcohol abuse or drug addiction.
• Chronic illness that, in the opinion of the Investigator, was at a stage where it might interfere with study conduct or completion.
• Moderate or severe acute illness/infection (according to Investigator judgment) on the day of planned vaccination or febrile illness (temperature >= 100.4 degree (°) Fahrenheit [38.0 °Celsius]). A prospective participant were not included in the study until the condition had resolved or the febrile event had subsided.
• 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, natural or adopted child) or in-laws of the Investigator or employee with direct involvement in the proposed study.
• History of serious adverse reaction to any influenza vaccine.
• Personal history of Guillain-Barré syndrome.
• Any condition that in the opinion of the Investigator would pose a health risk to the participants if enrolled or could interfere with the evaluation of the vaccine.
• Personal history of clinically significant developmental delay (at the discretion of the Investigator), neurologic disorder, or seizure disorder.
• Known seropositivity for human immunodeficiency virus, hepatitis B, or hepatitis C.

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

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org