Duration of hospital stay varied from < 1 to 96 days (median 19, IQR 12-38), duration of PICU stay was between < 1 and 50 days (median 11, IQR 6-18). In 70% of patients, PICU admission occurred at the day of hospital admission or within one day afterwards (range 0-10 days). In one child, the influenza infection was assumed to be nosocomial, with start of influenza symptoms and transfer to the PICU 9 days after initial hospitalisation due to complicated pneumonia caused by Mycoplasma pneumoniae.