Clinical Research Directory

Inclusion Criteria: Participants must meet all of the following inclusion criteria to be eligible for inclusion in the study: 1. Infant ≤12 months (≤360 days) of age on the hospitalisation date. 2. Index date within the time period for data collection (approximately 01 March 2025 - 28 February 2027) 3. Hospitalised with acute respiratory illness meeting the protocol-defined clinical case definition, and for whom RSV testing results from a specimen collected 10 days prior to hospital admission through 3 days after a hospital admission are known. 4. Infant born to a birth mother eligible to receive ABRYSVO vaccination, with infant date of birth on or after 17 February 2025. Exclusion Criteria: Participants meeting any of the following criteria will not be included in the study: 1. Infant born at \<28 weeks and 0/7 days of gestational age. 2. Infant received any licensed or investigational RSV preventive product (e.g., palivizumab, nirsevimab, active RSV vaccine) since birth. 3. Infant received ≥1 blood transfusion or other blood products containing antibody (e.g., fresh frozen plasma) since birth. 4. Infant born to a birth mother who received any other licensed or investigational RSV vaccine during this pregnancy. 5. Infant born to a birth mother for whom ABRYSVO vaccination status cannot be confirmed in available data sources.