Viral lower respiratory tract infections (LRTIs) in children during their first year of life are predominantly caused by respiratory syncytial virus (RSV), which is the leading epidemiological agent responsible for these infections globally NICE NG9. Other significant viral agents include influenza viruses, parainfluenza viruses, adenoviruses, human metapneumovirus, and rhinoviruses, but RSV remains the primary pathogen especially in infants under 12 months NICE NG9[Li et al. 2022].
RSV is highly prevalent and is the main cause of bronchiolitis and pneumonia in this age group, contributing substantially to hospital admissions and morbidity worldwide NICE NG9[Asseri 2025]. The burden of RSV-related acute lower respiratory infections is particularly high in infants younger than 1 year, with seasonal epidemics leading to peaks in disease incidence NICE NG9[Li et al. 2022].
Influenza viruses also contribute to viral LRTIs in infants, though less frequently than RSV, and their impact varies seasonally and geographically NICE CKS[Li et al. 2022]. Other viruses such as parainfluenza and adenoviruses are less common but still recognized causes of LRTIs in this population NICE NG9[Asseri 2025].
Recent clinical trials and epidemiological studies continue to emphasize RSV as the primary target for preventive interventions, including monoclonal antibodies like nirsevimab, underscoring its dominant role in infant viral LRTIs NICE NG9[Arbetter et al. 2025].
Key References
- Palivizumab SmPC
- Ribavirin SmPC
- CKS - Cough - acute with chest signs in children
- NG9 - Bronchiolitis in children: diagnosis and management
- CKS - Influenza - seasonal
- Ceftazidime with avibactam SmPC
- (Li et al., 2022): Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis.
- (Arbetter et al., 2025): Lower Respiratory Tract Infections Following Respiratory Syncytial Virus Monoclonal Antibody Nirsevimab Immunization Versus Placebo: Analysis From a Phase 3 Randomized Clinical Trial (MELODY).
- (Asseri, 2025): Respiratory Syncytial Virus: A Narrative Review of Updates and Recent Advances in Epidemiology, Pathogenesis, Diagnosis, Management and Prevention.