Mucosal Cytokine Profile of Patients (Type I and III Interferons, Pro-inflammatory Cytokines)

Among children aged ≤ 6 months included in the ENVIE study, the ENVIE\_ancillaire study will be offered to cases of RSV infection or to controls. The study involves a nasopharyngeal swab using a FLOQ-SWAB™ swab and a fingertip sample (dextro type). These samples will be collected specifically for the purpose of studying immunity. A blood sample may also be requested for children weighing ≥5 kg who are included in the ENVIE\_ancillaire study. The purpose of this sample collection will be to conduct an advanced immunological study