This is a single-center, randomized, open-label trial designed to explore the interaction between mucosal microbiota colonization in the nasal cavity and gut and the immune response to an intranasal live attenuated influenza vaccine (LAIV). The study plans to enroll 200 children and adolescents aged 6-17 years, with approximately 50% in the 6-11 years age group and 50% in the 12-17 years age group. Participants and their guardians must be able and willing to comply with the clinical trial protocol and provide informed consent. Eligible participants will be randomly assigned in a 1:1 ratio, stratified by age groups, to either the immediate vaccination group or the delayed vaccination group. Nasal swabs will be collected for all participants of both the immediate vaccination group or the delayed vaccination group after randomization for the detection of nasal and gut microbiota. Then, the immediate vaccination group will receive one dose of 0.2 mL of LAIV 28 days after randomization, while the delayed vaccination group will receive one dose of 0.2 mL of LAIV 56 days after randomization. Blood and mucosal samples (nasal stool) will be collected on the day before vaccination and on 28 days after vaccination for humoral and mucosal immunogenicity analysis. Moreover, the occurrence of adverse events within 28 days after vaccination will be collected.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
200
This vaccine is produced by Changchun BCHT Biotechnology Co.
This vaccine is produced by Changchun BCHT Biotechnology Co.
Haizhou District Center for Disease Control and Prevention
Lianyungang, Jiangsu, China
The level of sIgA antibodies (ng/mL) against the vaccine strain in nasal secretions at 28 days post-vaccination
Measured by Meso Scale Discovery
Time frame: Day 28 post-vaccination
Changes in the density of nasal mucosal bacterial colonization (CFU/mL) compared to baseline
Measured by 16s RNA or metagenomic analysis
Time frame: Day 28 post-vaccination
Changes in the abundance (α Diversity and β Diversity) of nasal mucosal bacterial colonization compared to baseline
Measured by 16s RNA or metagenomic analysis
Time frame: Day 28 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
Time frame: Day 28 post-vaccination
Changes in the density of gut bacterial colonization (CFU/mL) compared to baseline
Measured by 16s RNA or metagenomic analysis
Time frame: Day 28 post-vaccination
Changes in the abundance (α Diversity and β Diversity) of gut bacterial colonization compared to baseline
Measured by 16s RNA or metagenomic analysis
Time frame: Day 28 post-vaccination
The incidence of adverse events (AEs) within 28 days post-vaccination
Time frame: within 28 days post-vaccination
Number of IFN-γ secreting cells in nasal mucosal epithelial cells in response to influenza virus-based synthetic peptide pools at Day 28 post-vaccination (Exploratory)
The number of IFN-γ secreting cells will be quantified using an ELISpot assay.
Time frame: Day 28 post-vaccination
Frequency of activated T-cell subsets in nasal mucosal epithelial cells at Day 28 post-vaccination (Exploratory)
The phenotype and activation status of local mucosal T-cell subsets were measured by flow cytometry.
Time frame: Day 28 post-vaccination
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.