Gut Microbiome and Immune Response in Severe RSV Infection in Vietnamese Infants (GUT-LUNG RSV)

Impact of the Gut Microbiome on Immune Response and Disease Severity in Acute Respiratory Syncytial Virus (RSV) Infection in Vietnamese Children: A Prospective Observational Study

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infection in young children, and a substantial proportion of severe cases occur in previously healthy infants. The gut-lung axis suggests that gut microbiome composition may modulate respiratory immune responses. This prospective observational study in Vietnam will compare gut microbiome profiles and systemic immune cytokine responses between infants with severe RSV infection and those with mild RSV infection, aiming to identify microbiome-immune signatures associated with disease severity.

Study Overview

• Status: Not yet recruiting
• Conditions: Bronchiolitis; Respiratory Syncytial Virus Infection; Viral Lower Respiratory Tract Infection (LRTI)

Detailed Description

This is a single-center, prospective observational study conducted at Vietnam National Children's Hospital in Hanoi over 48 months. Approximately 250 infants aged 1-24 months with RT-PCR-confirmed RSV lower respiratory tract infection will be enrolled and classified into severe vs mild groups based on need for advanced respiratory support (HFNC/CPAP/invasive ventilation) and/or PICU admission versus no/low-flow oxygen requirement. Stool samples collected within the first 24 hours of admission will undergo 16S rRNA sequencing (V3-V4 region) to characterize gut microbiome diversity and taxa abundance. Blood samples collected within the first 24 hours will be used to quantify key cytokines (e.g., TNF-α, IL-6, IL-8, IL-1β, IFN-γ, IL-10, IL-17A, IL-22) using ELISA; immune cell subsets may be assessed by flow cytometry. Clinical severity will be assessed using standardized pediatric scores (PRISM III, PELOD, pSOFA) and treatment outcomes will be recorded. The study will evaluate associations among microbiome features, immune response markers, and RSV severity to propose candidate integrated biomarkers for early risk stratification.

• Study Type: Observational
• Enrollment (Estimated): 250

Contacts and Locations

• Study Contact: Name: Phuc H Phan, M.D.; Phone Number: +84912880105; Email: phucph@nch.gov.vn

Study Locations

• Vietnam
  • Hanoi, Vietnam
    • Vietnam National Children's Hospital
    • Contact: Phuc H Phan, M.D; Phone Number: +84912880105; Email: phucph@nch.gov.vn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Infants with acute lower respiratory tract infection and RT-PCR-confirmed RSV presenting to Vietnam National Children's Hospital

Description

Inclusion Criteria:

Age 1 to 24 months RT-PCR positive for RSV from respiratory specimen Symptoms consistent with acute lower respiratory tract infection Parent/legal guardian provides informed consent

Exclusion Criteria:

Prematurity <32 weeks gestation or birthweight <1500 g Chronic conditions (e.g., congenital heart disease, chronic lung disease, chronic liver/kidney disease) Primary or acquired immunodeficiency Severe malnutrition (weight-for-age Z-score < -3 SD) Antibiotic use within 2 weeks before admission Probiotic use within 4 weeks before admission Co-infection with other pathogens (viral/bacterial) Stool sample not obtained within 24 hours of admission

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Severe RSV group: infants requiring HFNC/CPAP/invasive ventilation and/or PICU admission; Mild RSV group: infants requiring no respiratory support or low-flow oxygen ≤2 L/min via nasal cannula

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Association between gut microbiome diversity/composition and RSV severity	Differences in gut microbiome diversity and taxonomic composition assessed by 16S rRNA sequencing (alpha diversity, beta diversity, and differential taxa abundance) between severe and mild RSV groups	Within 24 hours of hospital admission

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Systemic cytokine response in severe versus mild RSV infection	Serum concentrations of inflammatory and regulatory cytokines (TNF-α, IL-6, IL-8, IL-1β, IFN-γ, IL-10, IL-17A, IL-22) measured by ELISA All cytokines will be measured using the same assay platform and reported in the same unit of concentration. Unit of measurement is pg/ml	Within 24 hours of hospital admission
Clinical severity scores in RSV infection measured by Pediatric Sequential Organ Failure Assessment (pSOFA) Score	Clinical severity scores in RSV infection measured by Organ dysfunction severity assessed using the Pediatric Sequential Organ Failure Assessment (pSOFA) score (range: 0-24), with higher scores indicating more severe organ dysfunction	within 24 h of hospitalization
Integrated microbiome-immune signature predicting severe RSV	Multivariable model performance (AUC/ROC; or adjusted odds ratios for selected taxa + cytokines)	Baseline (first 24h) predicting severity classification during index hospitalization
ICU resource utilization	ICU-free days: calculated as 28 minus ICU length of stay for patients discharged alive before Day 28; assigned 0 for patients who die before Day 28 or remain in ICU on/after Day 28. Ventilator-free days: calculated as 28 minus days of invasive mechanical ventilation for patients alive and ventilated <28 days; assigned 0 for patients who die before Day 28 or remain ventilated on/after Day 28. Vasopressor-free days: calculated as 28 minus days receiving vasoactive agents for patients alive and requiring vasoactives <28 days; assigned 0 for patients who die before Day 28 or remain on vasoactives on/after Day 28. Discontinuation requires ≥12 hours without vasoactive support	Up to day 28

Collaborators and Investigators

• Sponsor: Phuc Huu Phan

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2029

Study Registration Dates

• First Submitted: February 11, 2026
• First Submitted That Met QC Criteria: February 11, 2026
• First Posted (Actual): February 18, 2026

Study Record Updates

• Last Update Posted (Actual): February 18, 2026
• Last Update Submitted That Met QC Criteria: February 11, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: infants; RSV; Biomarkers; gut microbiome; Vietnam; 16S rRNA; Bronchiolitis; Lower respiratory tract infection; Gut-lung axis
• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Lung Diseases; Bronchial Diseases; Lung Diseases, Obstructive; Bronchitis; Pneumovirus Infections; Paramyxoviridae Infections; Mononegavirales Infections; Respiratory Syncytial Virus Infections; Bronchiolitis
• Other Study ID Numbers: 41/BVNTW-HĐĐĐ

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