The number of patients admitted to an ICU with H1N1 2009 according to study week is displayed in Figure 1 . In 2010 the onset of the epidemic was delayed (by five weeks) and the peak incidence was lower. The impact on ICU services was significantly lower in 2010 with peak daily ICU bed occupancy being 7.5 (95% CI, 6.5 to 8.6) per million inhabitants in 2009 compared with 2.4 (95% CI, 1.8 to 3.0) per million inhabitants in 2010 (P < 0.001) ( Table 1) .