Mucosal and Systemic Immune Responses Induced by an Intranasal Influenza Live Attenuated Vaccine

Mucosal and Systemic Immune Responses Induced by an Intranasal Influenza Live Attenuated Vaccine: A Single-Center, Open-Label, Single-Arm Clinical Study

This is a single-center, open-label, single-arm clinical trial designed to evaluate the mucosal and systemic immune responses induced by an intranasal influenza live attenuated vaccine, and to explore the correlation between the two. The study plans to recruit 60 healthy volunteers aged 14-17 years, with a male-to-female ratio of 1:1. Participants and their guardians must be able and willing to comply with the clinical trial protocol and provide informed consent. Eligible participants will receive a single 0.2 mL dose of LAIV prior to the influenza season. Information on participants' historical vaccination records, baseline demographic data, and past health status will be collected. Nasal specimens (nasal secretions and nasal mucosal cells) and blood samples (serum and PBMCs) will be collected on Day 0 (before vaccination), Day 7, and Day 28 after vaccination for transcriptome sequencing and immunogenicity analysis. In addition, fecal samples will be collected on Day 0 (before vaccination), Day 7, and Day 28 after vaccination for intestinal microbiota detection.

Study Overview

• Status: Active, not recruiting
• Conditions: Influenza
• Intervention / Treatment: Biological: LAIV

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Phase 4

Contacts and Locations

Study Locations

• China
  • Jiangsu
    • Lianyungang, Jiangsu, China
      • Haizhou District Center for Disease Control and Prevention

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Individuals aged 14-17 years.
2. Volunteers and their guardians are able and willing to comply with the requirements of the clinical trial protocol and sign the informed consent form.

Exclusion Criteria:

1. Allergy to any component of the vaccine product, including eggs, excipients, or gentamicin sulfate.
2. Individuals with acute illnesses, severe chronic illnesses, acute exacerbations of chronic illnesses, or fever.
3. Pregnant or lactating women.
4. Individuals with Leigh syndrome who are receiving treatment with aspirin or aspirin-containing medications.
5. Individuals with immunodeficiency, immunosuppression, or those undergoing immunosuppressive therapy.
6. Individuals with uncontrolled epilepsy, other progressive neurological disorders, or a history of Guillain-Barré syndrome.
7. Individuals with rhinitis or asthma.
8. Individuals with a personal or family history of seizures, chronic diseases, epilepsy, or allergic tendencies.
9. Individuals who have received immunoglobulin injections within the last 3 months prior to vaccination.
10. Individuals who have used other live attenuated vaccines within 1 month prior to vaccination.
11. Individuals planning to use antiviral drugs for influenza within 48 hours before or 2 weeks after vaccination.
12. Individuals planning to use any other intranasal medication within 2 days after vaccination.
13. Subjects with underlying gastrointestinal diseases, including but not limited to inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), chronic diarrhea, peptic ulcer, and intestinal polyps.
14. Subjects with metabolic diseases, such as diabetes mellitus, obesity (BMI ≥ 25.9 kg/m²), hyperlipidemia, or metabolic syndrome.
15. Subjects who have used antibiotics, probiotics, or other drugs that may affect the intestinal microbiota within the past 3 months.
16. Other circumstances in which the subject is deemed unsuitable for participation in the study by the investigator.

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 vaccination group (Self-Controlled)	Biological: LAIV; This vaccine is produced by Changchun BCHT Biotechnology Co.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The level of IgG antibodies (ng/mL) against the vaccine strain in serum at 28 days post-vaccination.	Measured by Enzyme-Linked Immunosorbent Assay (ELISA)	Day 28 post-vaccination
The level of sIgA antibodies (AU/mL) against the vaccine strain in nasal secretions at 28 days post-vaccination.	Measured by Enzyme-Linked Immunosorbent Assay (ELISA)	Day 28 post-vaccination

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The levels of cytokines in serum at 7 days post-vaccination.	Measured by Meso Scale Discovery	Day 7 post-vaccination
The levels of cytokines in nasal mucosal secretions at 7 days post-vaccination.	Measured by Meso Scale Discovery	Day 7 post-vaccination
The levels of cytokines in serum at 28 days post-vaccination.	Measured by Meso Scale Discovery	Day 28 post-vaccination
The levels of cytokines in nasal mucosal secretions at 28 days post-vaccination.	Measured by Meso Scale Discovery	Day 28 post-vaccination
The level of IgG antibodies (ng/mL) against the vaccine strain in serum at 7 days post-vaccination.	Measured by Enzyme-Linked Immunosorbent Assay (ELISA)	Day 7 post-vaccination
The level of neutralizing antibodies (NT50 and IC50, ng/mL) against the vaccine strain in serum at 28 days post-vaccination.	Measured by Neutralization Assay	Day 28 post-vaccination
The gene expression levels in PBMCs (Peripheral Blood Mononuclear Cells) at 7 days post-vaccination.	Measured by Bulk Ribonucleic Acid Sequencing.	from baseline (pre-vaccination) to 7 days post-vaccination
The gene expression levels in nasal mucosal cells at 7 days post-vaccination.	Measured by Bulk Ribonucleic Acid Sequencing.	from baseline (pre-vaccination) to 7 days post-vaccination
The gene expression levels in PBMCs (Peripheral Blood Mononuclear Cells) at 28 days post-vaccination.	Measured by Bulk Ribonucleic Acid Sequencing.	Day 28 post-vaccination
The gene expression levels in nasal mucosal cells at 28 days post-vaccination.	Measured by Bulk Ribonucleic Acid Sequencing.	Day 28 post-vaccination
The level of sIgA antibodies (AU/mL) against the vaccine strain in nasal secretions at 7 days post-vaccination.	Measured by Enzyme-Linked Immunosorbent Assay (ELISA)	Day 7 post-vaccination

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in the abundance of intestinal microbiota compared with baseline (Exploratory).	Measured by 16s RNA or metagenomic analysis	Day 28 post-vaccination
Changes in the levels of fecal or serum metabolites compared with baseline (Exploratory)	Ultra-High Performance Liquid Chromatography-Mass Spectrometry	Day 28 post-vaccination

Collaborators and Investigators

• Sponsor: Jiangsu Province Centers for Disease Control and Prevention
• Investigators: Principal Investigator: Jing-Xin Li, PhD, Jiangsu Provincial Center for Diseases Control and Prevention

Study record dates

Study Major Dates

• Study Start (Actual): October 12, 2025
• Primary Completion (Estimated): November 10, 2025
• Study Completion (Estimated): May 10, 2026

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: November 14, 2025
• First Posted (Actual): November 18, 2025

Study Record Updates

• Last Update Posted (Actual): November 18, 2025
• Last Update Submitted That Met QC Criteria: November 14, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Keywords: Mucosal Immunity; Intranasal Influenza Live Attenuated Vaccine; Systemic Immunity
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Influenza, Human
• Other Study ID Numbers: JSJKYMS002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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