A27-04 Filling the Knowledge Gap: First Characterization of Neonatal RSV Infection in Latin America — Clinical Features and Severity From Medellin, Colombia (2022-2024)

Rationale Respiratory Syncytial Virus RSV is the leading cause of lower respiratory infection and hospitalization in children, specially during the first six months of life. Neonates are highly vulnerable due to immune immaturity and severe respiratory complications. Early severe RSV infection increases the risk of recurrent wheezing and childhood asthma. Clinical data on neonatal RSV and differences from non-RSV infections remain limited worldwide. This study aimed to describe clinical characteristics and outcomes of neonates with laboratory-confirmed respiratory syncytial virus (RSV) infection and to compare them with neonates with non-RSV acute respiratory infections in two tertiary centers in Medellín, Colombia (2022-2024) Methods Analytical observational cohort. We included neonates admitted with acute respiratory infection. Exclusion criteria were absence of antigen testing (immunofluorescence) and/or multiplex PCR (FilmArray). Variables were extracted from medical records. We report absolute and relative frequencies, and medians with interquartile ranges (IQR). Group comparisons used chi-square and Mann-Whitney U tests (two-sided, significance p < 0.05) Results We analyzed 372 patients; 108 (29%) were RSV-positive. RSV was identified by antigen testing in 96.3%, by multiplex PCR in 31.5%, and by both methods in 27.8%. Median age at admission was 16 days (IQR 14-20). No RSV-related deaths occurred. As detailed in Table 1, compared with non-RSV infections, RSV infection showed significantly higher rates of respiratory distress, crackles, wheezing, and lower frequency of fever, as well as greater need for respiratory support (oxygen therapy, high-flow nasal cannula, invasive ventilation), higher admission to intensive care, and more complications (notably atelectasis and respiratory failure) (all p < 0.05) Conclusions The highest hospitalization burden from RSV occurs within the first 6 months of life, especially the first 3 months (50%). Unlike countries with distinct seasonal peaks, Colombia experiences year-round circulation, maintaining continuous neonatal vulnerability. Although many neonatal cohorts emphasize comorbidities (prematurity, congenital heart disease), our data show that term neonates also constitute a high-risk group for severe RSV, challenging a prematurity-centric paradigm. Findings support preventive strategies in pregnancy and the immediate neonatal period (e.g., maternal immunization and long-acting monoclonal antibodies) to mitigate severe neonatal RSV disease.