An observational study in Respiratory Syncytial Virus Infection, Bronchiolitis and Viral Lower Respiratory Tract Infection (LRTI), sponsored by Phuc Huu Phan. Not yet recruiting at 1 site in Vietnam. Open to participants aged 1 Month to 24 Months. Per ClinicalTrials.gov, last updated 2026-02-18.
Sponsored by Phuc Huu Phan · Observational
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.
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.
306 studies on the registry are indexed under Respiratory Syncytial Virus Infections; 50 are open to participants now.
This study's planned enrollment of 250 is below the median of 375 across 76 observational studies indexed under Respiratory Syncytial Virus Infections.
Browse Respiratory Syncytial Virus Infections studies →Phuc Huu Phan is the lead sponsor of 2 studies on the registry; 2 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Infants with acute lower respiratory tract infection and RT-PCR-confirmed RSV presenting to Vietnam National Children's Hospital
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
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
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
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Mild RSV group: infants requiring no respiratory support or low-flow oxygen ≤2 L/min via nasal cannula
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
Time frame: Within 24 hours of hospital admission
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
Time frame: 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
Time frame: 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)
Time frame: 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
Time frame: Up to day 28
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
This study is not yet recruiting, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Respiratory Syncytial Virus Infections →
Phuc Huu Phan