On the day of specimen collection for viral culture, demographic, chest radiographic and respiratory data were recorded, as were clinical features. In three out of four patients on mechanical ventilation after intubation, the total respiratory compliance was calculated from ventilator settings as follows (ml/cmH 2 O): tidal volume/(plateau -end-expiratory pressure). From the radiographic score (ranging from 0 to 4 depending on the number of quadrants with radiographic opacities), the ratio of arterial oxygen tension to fractional inspired oxygen, the level of positive end-expiratory pressure and the compliance, the LIS was calculated [22] . (LIS ranges between 0 and 4, with values up to 2.5 denoting ALI and those above 2.5 ARDS.) None of the patients had visible oropharyngeal vesicles.