Evaluation in Practice of the Impact of NIrsevimab on EmeRgency Use for BRONCHIOlitis

Plain-language summary

In July 2023, the Food and Drug Administration approved nirsevimab (Beyfortus®), a long-acting monoclonal antibody, for passive immunization to prevent RSV-associated lower respiratory tract infection (Bronchiolitis) among infants and young children. In Europe, The European Medicines Agency approved the use of BEYFORTUS in October 2022. In France, The Haute Autorité de Santé (HAS) approved the use of BEYFORTUS in July 2023 starting in September 2023. Beyfortus is administered as a single intramuscular injection prior to or during RSV season. This single dose may provide protection during the whole RSV season. The safety and efficacy of Beyfortus® were supported by three clinical trials (1-3). The key measure of efficacy was the incidence of medically attended RSV lower respiratory tract infection (MA RSV LRTI ) evaluated during the 150 days after Beyfortus® administration. Beyfortus® reduced the risk of MA RSV LRTI by approximately 70% to 75% relative to placebo. The objective of this observational study is to assess in the real-world the effectiveness of nirsevimab on the Emergency Department use for bronchiolitis as well on the effectiveness of nirsevimab to reduce hospitalization and healthcare usage in France where a national campaign to administer nirsevimab to young infants stated on September 14th, 2023. Type of study Retrospective observational study of medical records which include systematic and prospective data on nirsevimab immunization status of patients visiting the Emergency Department. Methodology This retrospective observational study will include two data set analysis. On one part, data from all infants presenting to the emergency department and diagnosed as having bronchiolitis will be retrieved from medical and nursing records and those who had been given nirsevimab will be compared with those who did not receive this medication prior to the ED visit. On the other part, since the investigators have included nirsevimab administration in their systematic data collection on immunization of all infants visiting our ED, the investigators will use the nirsevimab immunization status of infants diagnosed as having bronchiolitis with those do not having bronchiolitis in order to assess the effectiveness (real-world effect) of nirsevimab on the ED use and hospitalization.

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