What is Known: • Bronchiolitis is one of the most common reasons for unplanned PICU admission. The most common virus causing bronchiolitis is RSV • Bronchiolitis severe enough to require admission to PICU is associated with frequent morbidity but has low mortality.

What is New: • RSV causes more severe bronchiolitis than other viruses. • Nearly half of all children admitted to PICU with RSV were previously healthy.