The Effectiveness of Early Immunisation With Nirsevimab on Preschool Wheezing in France, Based on an Analysis of Data From the French Health System Database.

Exclusion Criteria

• •\- Infants born in Overseas Departments and Territories (Guadeloupe, Martinique, Guyana, La Réunion, Mayotte, Saint-Pierre-et-Miquelon, French Polynesia, Nouvelle-Calédonie, Wallis-et-Futuna, French Southern and Antarctic Lands, Clipperton island)
• •Same-sex twins, as they cannot be differentiated in the French Medicalization of Information Systems Program (PMSI)
• •Infants born between 06/02/2023 and 31/01/2024 in a maternity unit that has not reported data on the immunization with nirsevimab
• •Infants whose mother had been vaccinated against RSV during pregnancy
• •Infants who received palivizumab immunization
• •Date of nirsevimab immunization not provided
• •Infants hospitalized for wheezing or RSV+ lower respiratory tract infection before receiving nirsevimab
• •Infants who were immunized after 12 months of age for outcomes collected between 2 and 6 years old
• •Infants who were immunized after 6 months of age for outcomes collected during the second year of life