To investigate the incidence of adverse events (AEs) and adverse drug reactions (ADRs) occurred following administration of Efluelda Tetra in adults aged 65 years or older under routine clinical practice, as per approved indications.

The study duration of each participation will be approximately 28 to 35 days. In the event that Visit 2 is not made, the study duration would be extended to 36 to 42 days.

Inclusion Criteria:

• Adults aged 65 years or older on the day of enrollment
• The informed consent form has been signed and dated
• Receipt of 1 dose of Efluelda Tetra on the day of enrollment according to the approved local product label

Exclusion Criteria:

• Previous history of enrollment in this study
• Participation at the time of study enrollment (or in the 4 weeks preceding the enrollment) or planned participation during the present study period in a clinical study investigating a vaccine, drug, medical device or medical procedure

Investigators will recruit participants after vaccination with Efluelda Tetra as per routine healthcare visits and according to approved local product labeling, at study centers (general hospitals or clinics located in Korea).

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