Chronologic Age at Hospitalization for Respiratory Syncytial Virus Among Preterm and Term Infants in the United States

INTRODUCTION: Respiratory syncytial virus (RSV) is the leading cause of hospitalization among infants in the United States, and the risk for RSV hospitalizations is greater for infants born preterm. Recent studies in preterm and term infants have shown that RSV hospitalization rates vary considerably depending on infant chronologic age. This study sought to aggregate the data available from published literature and from nationally representative databases of US infant hospitalizations to generate a composite description of the effect of young chronologic age on RSV hospitalizations among US preterm and term infants by individual month of age. METHODS: Data describing the relative incidence of RSV hospitalizations by individual month of chronologic age during the first year of life were obtained from recently published studies, the 2006–2011 National Inpatient Sample databases, and the 2006 and 2009 Kids Inpatient Databases. RESULTS: All data sources showed that ≥20% of infant RSV hospitalizations occurred in the second month of life and >50% and >75% of RSV hospitalizations were observed during the first 3 and 6 months of life, respectively. These findings were consistent for both preterm and term infants. CONCLUSION: Data from multiple sources demonstrate that the greatest risk of RSV hospitalization occurs during the first 6 months of life among US preterm and term infants. Strategies to prevent infant RSV hospitalizations should be targeted to infants during the first months of life. FUNDING: AstraZeneca.