Post-marketing Surveillance Study for the Safety of Efluelda® Pre-filled Syringe

Post-marketing Surveillance Study for the Safety of Efluelda® Pre-filled Syringe, a High-dose Trivalent Influenza Vaccine Administered to Adults 65 Years or Older in the Republic of Korea

To objective of this study is to investigate the incidence of adverse events (AEs) and adverse drug reactions (ADRs) occurred following administration of Efluelda® in adults aged 65 years or older under routine clinical practice, as per approved indications This is an open-label, multi-center, observational active safety surveillance study, designed to be conducted under standard healthcare setting of the Republic of Korea, in accordance with "Regulation on the Operation of Risk Management Plans".

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Volunteers; Influenza Immunization
• Intervention / Treatment: Biological: Efluelda® Pre-filled syringe

• Study Type: Observational
• Enrollment (Estimated): 670

Contacts and Locations

• Study Contact: Name: Trial Transparency email recommended (Toll free for US & Canada); Phone Number: option 6 800-633-1610; Email: contact-us@sanofi.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

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

600 evaluable participants will be included and will include male and female adults aged 65 years and older.

Description

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® 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

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

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Efluelda® Vaccination Group; Adults aged 65 years of age or older will receive 1 dose of Efluelda® vaccination intramuscularly on Day 1	Biological: Efluelda® Pre-filled syringe; Pharmaceutical Form: Suspension for injection in a pre-filled syringe Route of Administration: Intramuscular administration

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occurrence of solicited injected site reactions.	Number of participants experiencing solicited injection site reactions	Up to 7 days after vaccination
Occurrence of solicited systemic reactions	Number of participants experiencing solicited systemic reactions	Up to 7 days after vaccination
Occurrence of unsolicited Adverse Events (AE)	Number of participants experiencing AEs	From vaccination to Visit 2 (up to approximately 42 days)
Occurrence of unsolicited Adverse Drug Reactions (ADR)	Number of participants experiencing ADRs	From vaccination to Visit 2 (up to approximately 42 days)
Occurrence of unexpected Adverse Events (AE)	Number of participants experiencing unexpected AEs	From vaccination to participant's last contact (up to approximately 42 days)
Occurrence of unexpected Adverse Drug Reactions (ADR)	Number of participants experiencing unexpected ADRs	From vaccination to participant's last contact (up to approximately 42 days)
Occurrence of Serious Adverse Events (SAE)	Number of participants experiencing SAEs	From vaccination to participant's last contact (up to approximately 42 days)
Occurrence of unexpected Serious Adverse Drug Reactions (SADR)	Number of participants experiencing unexpected SADRs	From vaccination to participant's last contact (up to approximately 42 days)
Occurrence of Adverse Event of Special Interest (AESI)	Number of participants experiencing AESIs	From vaccination to participant's last contact (up to approximately 42 days)

Collaborators and Investigators

• Sponsor: Sanofi

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): February 22, 2029
• Study Completion (Estimated): March 20, 2029

Study Registration Dates

• First Submitted: December 2, 2025
• First Submitted That Met QC Criteria: December 2, 2025
• First Posted (Actual): December 15, 2025

Study Record Updates

• Last Update Posted (Actual): March 31, 2026
• Last Update Submitted That Met QC Criteria: March 30, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Flu; Efluelda®
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Influenza, Human
• Other Study ID Numbers: FIM00018; U1111-1331-8205 (Registry Identifier: ICTRP)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: 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

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes