Preliminary Safety Assessment of a Quadrivalent Subunit Influenza Vaccine in China: A Phase IV Study

Preliminary Safety Assessment of a Quadrivalent Subunit Influenza Vaccine Following Post-Marketing in China: An Open-Label, Single-Arm Clinical Trial

This study evaluates the safety of the quadrivalent subunit influenza vaccine in individuals aged 3 years and older in Jiangsu Province, China. The primary objectives are to assess the occurrence of very rare adverse reactions (incidence <0.01%), investigate the incidence of cerebral infarction following vaccination, and evaluate the incidence of systemic adverse events among participants aged 9 to 17 years.

Study Overview

• Status: Completed
• Conditions: Influenza Vaccine
• Intervention / Treatment: Biological: quadrivalent subunit influenza vaccine

Detailed Description

This is an open-label, single-arm, non-controlled, real-world safety study of the quadrivalent subunit influenza vaccine, designed to systematically track and evaluate the overall safety profile following vaccine administration.

The core objectives of this study are as follows:

1. To assess the occurrence of rare adverse reactions with an incidence rate of less than 0.01% after vaccination;
2. To investigate the incidence of cerebral infarction events following receipt of the study vaccine;
3. To evaluate the incidence of systemic adverse events after vaccination among participants aged 9 to 17 years.

A total of 3,105 eligible participants aged 3 years and older who voluntarily receive the vaccine will be enrolled. All enrolled participants will be administered a single 0.5 mL intramuscular dose of the quadrivalent influenza subunit vaccine.

The safety monitoring protocol is arranged as follows:

1. 30-minute immediate observation: On-site monitoring will be conducted at the vaccination clinic immediately after injection to detect immediate adverse reactions.
2. 28-day systematic safety follow-up: Participants will perform daily self-monitoring of adverse events within 28 days after vaccination. Investigators will conduct two on-site centralized follow-up visits on Day 7 and Day 28 post-vaccination respectively, to verify and collect adverse event data.
3. 6-month serious adverse event monitoring: The occurrence of serious adverse events will be monitored via spontaneous reporting by participants within 6 months after vaccination.

• Study Type: Interventional
• Enrollment (Actual): 3105
• Phase: Phase 4

Contacts and Locations

Study Locations

• China
  • Jiangsu
    • Dongtai, Jiangsu, China, 224200
      • Dongtai Center for Disease Control and Prevention
    • Lianshui, Jiangsu, China, 223400
      • Lianshui County Center for Disease Control and Prevention

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria

1. Healthy individuals aged 3 years or above.
2. The participant (and/or their guardian/legal representative) has provided informed consent, voluntarily agreed to participate, signed the Informed Consent Form, and is able to comply with the requirements of this study protocol.

Exclusion Criteria

1. Individuals with a known allergy to any component of the vaccine, including eggs, excipients, formaldehyde, or Triton N-101.
2. Individuals suffering from an acute illness, severe chronic disease, an acute exacerbation of a chronic disease, common cold, or fever.
3. Individuals with uncontrolled epilepsy or other progressive neurological disorders, or a history of Guillain-Barré syndrome.
4. Any other condition considered by the investigator as inappropriate for participation in this study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: The quadrivalent influenza subunit vaccine Group; receive a single 0.5 mL intramuscular dose of the quadrivalent influenza subunit vaccine	Biological: quadrivalent subunit influenza vaccine; one dose of quadrivalent subunit influenza vaccine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse Events (AEs)	Occurrence of adverse events (AEs) within 30 minutes, 7 days, and 28 days after vaccination	30 minutes, 7 days, and 28 days after vaccination
Adverse Drug Reactions（ADR）	Incidence of known adverse drug reactions (ADRs) within 30 minutes, 7 days, and 28 days after vaccination	30 minutes, 7 days, and 28 days after vaccination
Serious Adverse Events (SAEs)	Occurrence of serious adverse events (SAEs) within 6 months after vaccination; Incidence of new adverse reactions following vaccination； Incidence of cerebral infarction following vaccination； Incidence of systemic adverse reactions following vaccination in individuals aged 9 to 17 years	6 months after vaccination

Collaborators and Investigators

• Sponsor: Ab&B Bio-tech Co., Ltd.JS
• Collaborators: Jiangsu Province Centers for Disease Control and Prevention

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2024
• Primary Completion (Actual): May 29, 2025
• Study Completion (Actual): May 29, 2025

Study Registration Dates

• First Submitted: July 14, 2026
• First Submitted That Met QC Criteria: July 14, 2026
• First Posted (Actual): July 17, 2026

Study Record Updates

• Last Update Posted (Actual): July 17, 2026
• Last Update Submitted That Met QC Criteria: July 14, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: safety; Quadrivalent Subunit Influenza Vaccine
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Influenza, Human
• Other Study ID Numbers: CTR20244333

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No