Our study showed that in Germany children < 1 year of age and children with chronic underlying diseases are the main paediatric risk groups for severe seasonal influenza infections. Influenza-associated pneumonia, secondary bacterial infections, ARDS and encephalitis/encephalopathy were frequent complications. The observed clinical characteristics were similar to the results from the U.S. and other countries [2, 4, 8, [12] [13] [14] [15] [16] [17] . However, children in our study were older (median 7.5 years) than in an ICU study in the U.S. (median 1.5 years) [12] . Fatalities also were reported only in two older children (8 and 14 years of age), whereas the majority of reported paediatric fatalities in the U.S. and Australia are below 5 years of age [14, 17] . In our study, ARDS occurred in 25% of the PICU children, in contrast to a retrospective chart review in an U.S. children's hospital with 27 PICU children diagnosed with seasonal influenza 2008/2009 [18] , which reported only 4% of ARDS.