Figure 2.

Histopathology lung severity score in infants who die due to RSV. Frequency of different pattern of lung histopathology was measured in 4 categories based on bronchiolitis (red bar), bronchitis (orange bar), and epithelial necrosis (gray bar) severity. Bronchiolitis score was: 0 = no remarkable lesions, 1 = minimal detectable epithelial degeneration in few bronchioles, 2 = epithelial degeneration in <10% of the airway lumen, 3 = epithelial degeneration in >10–50% of the lumen with cell debris and neutrophils, 4 = circumferential bronchiolitis with dense adventitial lymphocytes in multiple bronchioles [15]. Abbreviation: RSV, respiratory syncytial virus.