Bronchiolitis is a lower respiratory tract infection, extremely common in pediatrics, and potentially serious. Bronchiolitis affects nearly 30% of infants under 2 years old each year, representing approximately 480,000 cases annually worldwide. Each year, 2 to 3% of infants under 1 year old are hospitalized for bronchiolitis. The virus primarily found worldwide and in France is RSV. Given the scale, frequency, and potential severity of the illness, several immunoprophylaxis methods have been developed.

Currently, there are two methods: the ABRYSVO vaccine, administered to pregnant women during the last month of pregnancy for immunization via the placenta through the transplacental passage of anti-RSV-A and RSV-B antibodies; or neonatal immunoprophylaxis with BEYFORTUS, which involves an intramuscular injection of the monoclonal antibody nirvesimab directly into the newborn immediately before discharge from the maternity ward during the epidemic period.

Currently, no superiority or difference has been described for either immunoprophylaxis method.

Inclusion Criteria:

• all term born neonates

Exclusion Criteria:

• postnatal transfert
• born at home or in birthing center

term born neonate