Severity of RSV Infections in Twins

Study Overview
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Brief Summary
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Respiratory syncytial virus (RSV) infection is the most common cause of severe lower respiratory tract infection (LRTI) in the pediatric population worldwide. Age at the time of infection, prematurity, multiparity, exposure to smoke and the level of passive immunity transmitted at birth are the main risk factors for lower respiratory infection associated with RSV. Other factors, including the innate immune response, respiratory microbiota, and intra-host viral heterogeneity, may also affect outcomes but are not fully considered in RSV infection. Exploring the impact of these factors is difficult due to the heterogeneity of the population which makes statistical adjustment difficult. Thus, twin models are useful in understanding the impact of the host on the environment, as twins often share similar exposure to infection and many risk factors, but not all are ie different prenatal and postnatal conditions, differential transfer of maternal antibodies and the genetic makeup of heterozygotes.

Official Title
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Phenotype Severity of RSV-infections in Twins During the First Year of Life

Conditions
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RSV Infection, Bronchiolitis

Intervention / Treatment
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* Other: Epidemiology


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Twins born at Hospices Civils de Lyon in the years 2012 to 2020 At least one twin hospitalized with positive RSV-PCR during the first year of life Exclusion Criteria: Major differential underlying disease between twins Death of a twin before the RSV epidemic period of the first year of life Nosocomial infection Lack of understanding of the study or questionnaire by parents Lack of parental consent

Ages Eligible for Study
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Maximum Age: 354 Days

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Twins<br>Twins identified from the birth cohort (Hospices Civils de Lyon) with at least one twin hospitalized for an acute RSV-infection | Other: Epidemiology<br>* Assessment of the discrepancy of clinical severity of RSV-infections between twin infants.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of discordant twin pairs in severity of Respiratory Syncytial Virus infections. | The primary outcome measure is the percentage of discordant twin pairs of at least one severity level on the WHO (World Health Organization) scale. The discrepancy in the level of severity is obtained by retrospective analysis of the data from the medical file. | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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RSV infections in twins, Bronchiolitis, very-severe-LRTI, severe-LRTI, LRTI, upper respiratory tract infection, RSV infection, Human, infant