Comparing of two different epidemic seasons of bronchiolitis

Acute bronchiolitis is the most common cause of hospitalizations in infants < 12 months of age and preventive efforts remain the most important strategy to date. Recently prophylaxis with palivizumab (PLV) was limited to preterm infants with < 29 weeks gestational age (wGA). We performed a single center analysis in preterm infants (GA between 30 and 32 weeks) and age < 12 months to compare prophylaxis with PLV and frequency and characteristics of bronchiolitis and bronchiolitis-related hospitalization in two consecutive epidemic seasons (S1 vs S2). We found a rising trend in rate of bronchiolitis and bronchiolitis-related hospitalization in S1 vs S2. Among hospitalization, we found an increased morbidity with an increase in the rate of mechanical ventilation in S2. Additionally, hospitalization occurred in subjects with younger chronological age in S2 compared with S1. Our result cannot be generalized because deriving from a single Center and further evaluation on wider simple size are warranted, but it suggests an increase in the incidence, gravity and precocity of bronchiolitis in 29–32 wGE preterm infants with the change in National guidelines for prophylaxis.