Multi-center, observational, active safety surveillance study in participants aged 6 to 35 months in Korea under routine clinical practices.

The planned duration of each participant's participation in the study will be 21 to 28 days.

Inclusion Criteria:

• Aged 6 to 35 months on the day of enrolment
• Informed consent form has been signed and dated by the parent or other legally acceptable representative
• Receipt of one dose of VaxigripTetra® on the day of inclusion in routine practice according to the approved local product insert

Exclusion Criteria:

- Participation at the time of study enrolment (or in the 4 weeks preceding the enrolment) or planned participation during the present study period in a clinical study investigating a vaccine, drug, medical device, or medical procedure

Participants aged 6 to 35 months will be enrolled after receipt of one dose of VaxigripTetra® during a routine health care visit.

Participants will be enrolled on the day of vaccination (first or second vaccination) and will be followed-up for only one vaccination.

Planned number of subjects: 670 subjects aged 6 to 35 months Planned number of country: 1 (Republic of Korea) Planned number of sites: 12

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://www.vivli.org