GMTs of influenza vaccine antibodies were measured using individual hemagglutination inhibition (HAI) assay for 4 influenza virus strains: A/H1N1 strain, A/H3N2 strain, B/Victoria lineage strain, and B/Yamagata lineage strain.

Analysis was performed on the per-protocol analysis set (PPAS)-subset of full analysis set (FAS) which included participants who received 1 dose of the study vaccine and had a post-vaccination blood sample. Only participants with data collected for each category at Day 29 [participants previously vaccinated] or Day 57 [participants previously unvaccinated] are reported.

Anti-influenza antibodies were measured using HAI assay for 4 influenza virus strains: A/H1N1 strain, A/H3N2 strain, B/Victoria lineage strain, and B/Yamagata lineage strain. SC was defined as either a pre-vaccination HAI titer less than (<) 10 (1/dilution) and a post-vaccination titer greater than or equal to (≥) 40 (1/dilution) or a pre-vaccination titer ≥ 10 (1/dilution) and a ≥ 4-fold increase in post-vaccination titer.

Analysis was performed on the PPAS-subset of FAS which included participants who received 1 dose of the study vaccine and had a post-vaccination blood sample. Only participants with data collected for each category at Day 29 [participants previously vaccinated] or Day 57 [participants previously unvaccinated] are reported.

GMTs of influenza vaccine antibodies were measured using HAI assay for 4 influenza virus strains: A/H1N1 strain, A/H3N2 strain, B/Victoria lineage strain, and B/Yamagata lineage strain.

Analysis was performed on the PPAS-subset of FAS which included participants who received 1 dose of the study vaccine and had a post-vaccination blood sample. Only participants with data collected for each category at Day 1 are reported.

Antibody titers were measured using HAI assay for 4 influenza virus strains: A/H1N1 strain, A/H3N2 strain, B/Victoria lineage strain, and B/Yamagata lineage strain.

Analysis was performed on the PPAS-subset of FAS which included participants who received 1 dose of the study vaccine and had a post-vaccination blood sample. Only participants with data collected for each category at Day 1 and Day 29 [participants previously vaccinated] or Day 57 [participants previously unvaccinated] are reported.

GMTR was the ratio of the individual titers post-vaccination over pre-vaccination. The GMTs of influenza vaccine antibodies were measured using HAI assay for 4 influenza virus strains: A/H1N1 strain, A/H3N2 strain, B/Victoria lineage strain, and B/Yamagata lineage strain.

Analysis was performed on the PPAS-subset of FAS which included participants who received 1 dose of the study vaccine and had a post-vaccination blood sample. Only participants with data collected for each category at Day 1 and Day 29 [participants previously vaccinated] or Day 57 [participants previously unvaccinated] are reported.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, i.e., pre-listed in the case report form (CRF) in terms of diagnosis and onset window post-vaccination. Immediate events were recorded to capture medically relevant unsolicited systemic AEs which occurred within the first 30 minutes after vaccination.

Safety analysis set included participants who received at least 1 dose of the study vaccine.

Solicited injection site reactions were reactions at and around the injection/administration site of the investigational medicinal product (IMP) observed and reported under the conditions (nature and onset) pre-listed in the protocol and CRF and considered as being related to the IMP administered at that site. Solicited systemic reactions were systemic AEs observed and reported under the conditions (nature and onset) pre-listed in the protocol and CRF, and those occurring during the specified collection period were always considered related to the IMP even if there was evidence of alternative etiology.

Safety analysis set included participants who received at least 1 dose of the study vaccine. Only participants with data collected for each category up to 7 days post vaccination are reported.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, i.e., pre-listed in the CRF in terms of diagnosis and onset window post-vaccination.

Safety analysis set included participants who received at least 1 dose of the study vaccine.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An MAAE was a new onset or a worsening of a condition that prompted the participant or participant's parent/legally acceptable representative to seek unplanned medical advice at a physician's office or emergency department.

Safety analysis set included participants who received at least 1 dose of the study vaccine.

An SAE was defined as any adverse event that, at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, or was other medically important event. An AESI was defined as one of scientific and medical concern specific to the Sponsor's study intervention or program, for which ongoing monitoring and rapid communication by the Investigator to the Sponsor was appropriate.

Safety analysis set included participants who received at least 1 dose of the study vaccine.