In 2009, an influenza pandemic was caused by a new influenza A/H1N1 virus (PIA). In more than 214 countries laboratory-confirmed PIA cases were reported, including over 18,097 deaths [3] . During this pandemic especially children appeared to be affected. In the USA, about 87,000 PIA hospitalizations (PIAH) and 1,280 fatalities occurred in children <18 years of age from April 2009 to April 2010, representing 32% of all PIAH and 10% of all PIA-associated fatalities in the US population [4] .