An Observational Study to Assess Nirsevimab Immunization Rates in Eligible Infants During Their First RSV Season in the Czechia

The primary objective of this study is to determine the nirsevimab immunization rate in eligible infants in their first RSV-season in Czechia. The study will focus on: 1. Assessing nirsevimab immunization rates among eligible infants (according to ČVS recommendation) in their first RSV-season in Czechia (i.e. across all geographies) 2. Assessing nirsevimab immunisation rates among the "catch-up cohort", i.e. all infants born between April and September. 3. Assessing nirsevimab immunization rate among the "in-season cohort", i.e. all infants born during the RSV season between October and March. Secondary objectives are: 1. To analyze reasons of parents to decide for or against immunization of their infant with nirsevimab. 2. To assess immunization rates for further subgroups, if sufficient sample for subgroup achieved, e.g. by: risk group (defined chronic condition or pre-term birth status) 3. To assess concordance of a parent survey results based on randomly sampled parent population using Computer-Assisted Self-Interviewing (CASI) for estimating immunization rates in Czechia with coverage calculated based on pharmacy sales data.