The effect of birth month on the risk of respiratory syncytial virus hospitalization in the first year of life in the United States.

Background: Respiratory syncytial virus (RSV) is the most common cause of severe respiratory illness in infants. To help direct targeted interventions and future RSV vaccine programs, we examined risk of RSV-related hospitalization by infant age and birth month.

Methods: We conducted Poisson regression analyses to evaluate birth month as a risk factor for RSV-related pediatric hospitalizations (identified by any mention of ICD-9-CM diagnosis codes: 466.