Evaluation of the Effect of Nirsevimab on Hospitalizations Due to RSV Infection in Infants Under One Year of Age.

Evaluation of the Effect of Nirsevimab on Hospitalizations Due to RSV Infection in Infants Under One Year of Age: A Case-Control Study

This study aims to evaluate the impact of Nirsevimab, a monoclonal antibody used for RSV prophylaxis, on reducing RSV- related hospitalizations. It will be conducted at 8 pediatric departments in Tuscany, Italy. First, a matched case-control study investigates the real-world effectiveness of Nirsevimab in preventing RSV-related lower respiratory tract infection (LRTI) hospitalizations during the RSV epidemic season 2024-2025. Second, a descriptive study examines how the Nirsevimab immunization campaign affects RSV epidemiology, focusing on patients' age, comorbidities, infection severity, and clinical outcomes. The findings aim to optimize RSV prevention strategies and inform public health policies.

Inclusion Criteria:

Case patients

• Age <12 months
• Diagnosis of LRTI (i.e., bronchiolitis and/or pneumonia) at admission
• Positive RSV PCR on nasopharyngeal swab Control patients
• Age <12 months
• Diagnosis of LRTI (i.e., bronchiolitis and/or pneumonia) at admission
• Hospitalized for conditions other than respiratory infections

Exclusion Criteria:

• Parental refusal
• Previous immunization with Palivizumab
• Previous maternal RSV vaccine immunization during pregnancy