RSV vs Influenza: Which causes more severe respiratory illness in children under 2-years-old?

According to a study, children under the age of 2 admitted to the hospital with a respiratory syncytial virus (RSV) had more severe respiratory illness than influenza and a higher risk for a complex hospital course.

In a retrospective cohort study, children <2 years who were admitted for influenza-associated lower respiratory tract infections (LRTI) and tested positive for influenza (n = 134; 11%) or RSV (n = 1094; 89%) were included.

Children who were hospitalized for influenza were significantly older than those hospitalized with RSV (336 days vs 165 days, P < 0.001). In addition, they were more like to present with an abnormal heart rate for their age (84.3% vs 73.5%, P < 0.01) as well as a fever (27.6% vs 18.9%, P = 0.02).

Patients admitted with RSV were significantly more likely to experience a complex hospital course and had a significantly higher rate of respiratory support.

Readmission rates were similar between patients admitted with RSV and influenza.

Reference
Tang KM, Hametz P, Southern W. RSV causes more severe respiratory illness than influenza in admitted children under 2-years-old. Pediatr Pulmonol. 2023;doi: 10.1002/ppul.26394. Epub ahead of print. PMID: 37014143.