Immunological and respiratory disorders were the most commonly reported underlying medical conditions in the pandemic season, for respectively 23 (35%) and 22 (34%) of the 65 fatalities (table 2). In the 2010-2011 season, cardiovascular disorders and absence of medical underlying conditions were most common, respectively for 12 (32%) and 10 (26%) of the 38 deaths. Underlying immunological disorders were more common in the 2009-2010 compared to the 2010-2011 season (p = 0.02), while cardiovascular disorders were significantly more common in the 2010-2011 season (p = 0.005). Overall, multiple underlying conditions were reported for 27 of the 103 cases (26%). Particularly, intellectual disability (100%), cardiovascular (76%) and metabolic disorders (75%) were found in combination with other underlying conditions (data not shown).