IRIS (Infection with RespIratory Syncytial Virus) is an observational, multi-center study enrolling infants with severe RSV infection and healthy controls. Inclusion criteria are age below two years and hospitalization due to RSV infection at three German sites. Exclusion criteria are premature birth, congenital or acquired bronchopulmonary or cardiac diseases, and immunodeficiency. Blood and respiratory specimens are collected upon admission, and RSV and other pathogens are analyzed by multiplex polymerase chain reaction (PCR). Further biomaterials including plasma, nasal lining fluid, blood cells, DNA, and RNA specimens are sampled in a dedicated biobank. Detailed information on demographic characteristics and medical history is recorded, as well as comprehensive clinical data including vital signs, medication, and interventions.

The IRIS study is designed as a multicentric, prospective, observational study initiated at Hannover Medical School, Germany. Upon enrollment, detailed data on demographic background, case histo-ry, clinical presentation, physical examination, diagnostic findings, treatment, and other patient related items is collected. Data on disease course, treatment, and complications is gathered. Blood and respiratory specimens are collected upon admission, and RSV and other pathogens are analyzed by multiplex polymerase chain reaction (PCR). Further biomaterials including plasma, nasal lining fluid, blood cells, DNA, and RNA specimens are sampled in a dedicated biobank (Hannover Unified Biobank). The study enrolls hospitalized children with confirmed RSV infection between the first month of life and second year of life. The diagnosis of RSV is evaluated by point-of-care testing (POCT, Sofia, Quidel, Kornwestheim, Germany), and positive findings are confirmed by polymerase chain reac-tion (PCR). Exclusion criteria are premature birth, congenital or acquired bronchopulmonary or car-diac diseases, and immunodeficiency. Healthy control probands are enrolled via recruitment of patients undergoing routine surgical procedures. Written informed consent is obtained from all parents and caregivers. Three local study centers in northern Germany (Hannover, Oldenburg, and Hildesheim) are contributing. All study sites are secondary or tertiary care hospitals and undergo extensive training in recruitment, biosample acquisition and processing, data collection and data entry, logistics, and security.

Inclusion Criteria:

• RSV Infection, confirmed by polymerase chain reaction (PCR)
• Need for hospitalisation

Exclusion Criteria:

• premature birth
• bronchopulmonary diseases
• cardiac diseases
• immunodeficiency

The study enrolls hospitalized children with confirmed RSV infection between the first month of life and second year of life. The diagnosis of RSV is evaluated by point-of-care testing, and positive findings are confirmed by polymerase chain reac-tion (PCR). Exclusion criteria are premature birth, congenital or acquired bronchopulmonary or car-diac diseases, and immunodeficiency.