This study is subject to several limitations, many of which relate to assumptions that were necessary for the modeled scenario. For example, in our baseline scenario we assumed that 12% of hospital capacity, across all provinces and countries, would be available to care for the surge of patients with influenza infections. In reality, surge capacity is likely to vary substantially between and within countries (and over time), but few data on this are available. Robust analytical frameworks are urgently needed to define and measure health system surge capacity in order to inform analyses of resource gaps for emergency response scenarios. The effectiveness of resources such as antiviral drugs, ventilators, and general hospital care for improving the survival rates among severe influenza cases is also surrounded by considerable uncertainty and may vary between settings. Our results show that, even if epidemiological parameters describing transmission and pathogenicity are kept constant, uncertainties in spare capacity and resource effectiveness lead to considerable uncertainties in estimates of avoidable mortalities rates. Nevertheless, the distributions of model outputs from our multivariate uncertainty analysis still showed some significant differences when compared across countries and across resource types (Figures 3 and 5) . Furthermore, it seems likely that spare capacity and resource effectiveness would be higher in more resource-rich settings, which would only strengthen the findings of this study in terms of the geographic distribution of resource gaps and avoidable mortalities.