Fig. 5

Virulence of sH3N2 compared to pH1N1 in terms of (a) excess all-cause death, (b) an excess respiratory death and (c) excess respiratory hospitalization. It is expressed as the ratio of the estimated risk of adverse events caused by sH3N2 infection relative to pH1N1. Values above one indicate higher estimated risk for sH3N2. Confidence intervals are calculated using a score confidence interval [32] as implemented in the riskscoreci function in the R package PropCIs