Respiratory Syncytial Virus-Load Kinetics and Clinical Course of Acute Bronchiolitis in Hospitalized Infants: Interim Results and Review of the Literature

Abstract

Respiratory Syncytial Virus (RSV) bronchiolitis is the leading cause of hospitalization in infants. The role of RSV load in disease severity is still debated. We present the interim results of a prospective monocentric study enrolling previously healthy infants hospitalized for RSV bronchiolitis, collecting nasopharyngeal aspirates every 48 h from admission to discharge, and evaluating RSV-load dynamics in relation to clinical outcome measures of bronchiolitis severity, including: need, type and duration of oxygen therapy, length of hospitalization, and the bronchiolitis clinical score calculated at admission. The results showed that the highest viral replication occurs within the first 48 hours after admission, with a significant decrease at subsequent time points (p < 0.0001). Moreover, higher RSV-RNA values were associated with the need for oxygen therapy (p = 0.03), particularly high-flow nasal cannulae type (p = 0.04), and longer duration of respiratory support (p = 0.04). Finally, higher RSV-load values were correlated with lower white blood cells, especially lymphocyte counts and C-reactive protein levels s (p = 0.03, p = 0.04, and p = 0.01, respectively), as well as with patients of a younger age (p = 0.02). These data suggest that RSV may actively contribute to the clinical severity of bronchiolitis, together with other potential non-viral factors.

Comparative analysis of Respiratory Syncytial Virus frequency rates and viral load in different patient cohorts in a University Hospital in São Paulo, Brazil, over an eight-year period (2005–2013)

“…Among young children who are particularly susceptible to severe RSV infections, higher viral loads have been associated with more severe clinical manifestations, including bronchiolitis and pneumonia. 1 , 7 , 13 , 14 , 15 , 16 These findings underscore the importance of viral load as a determinant of disease severity and highlight the need for early identification and intervention in high-risk pediatric populations.…”

Comparative analysis of Respiratory Syncytial Virus frequency rates and viral load in different patient cohorts in a university hospital in Sao Paulo, Brazil, over an eight-year period (2005-2013)

“…The viral load of RSV can vary substantially among infected individuals and is influenced by multiple factors such as age, immune status, and comorbidities. Among young children who are particularly susceptible to severe RSV infections, higher viral loads have been associated with more severe clinical manifestations, including bronchiolitis and pneumonia 1,6,[12][13][14][15] . These findings underscore the importance of viral load as a determinant of disease severity, and highlight the need for early identification and intervention in high-risk pediatric populations.…”