Multinational comparison of excess mortality rates and age distribution of deaths associated with the 2009 A/H1N1 pandemic and seasonal epidemics, based on a literature review.

For studies providing analyses of cause-specific mortality, we report estimates based on respiratory outcomes, as we believe is the most reliable cause of death to estimate the burden of this pandemic. If respiratory estimates were not available, we report estimates from cardio-respiratory mortality, and when that was not available, from all-cause mortality.CI: confidence intervals.*Poisson model driven by ILI.**Poisson model driven by viral activity.†Calculated as [2009 pandemic excess mortality rate]/[average seasonal excess mortality rate].