Global Mortality Estimates for the 2009 Influenza Pandemic from the GLaMOR Project: A Modeling Study

Background:assessing the mortality impact of the 2009 influenza a h1n1 virus (h1n1pdm09) is essential for optimizing public health responses to future pandemics. the world health organization reported 18,631 laboratory-confirmed pandemic deaths,but the total pandemic mortality burden was substantially higher. we estimated the 2009 pandemic mortality burden through statistical modeling of mortality data from multiple countries.methods and findings:we obtained weekly virology and underlying cause-of-death mortality time series for 2005-2009 for 20 countries covering ∼35% of the world population. we applied a multivariate linear regression model to estimate pandemic respiratory mortality in each collaborating country. we then used these results plus ten country indicators in a multiple imputation model to project the mortality burden in all world countries. between 123,000 and 203,000 pandemic respiratory deaths were estimated globally for the last 9 mo of 2009. the majority (62%-85%) were attributed to persons under 65 y of age. we observed a striking regional heterogeneity,with almost 20-fold higher mortality in some countries in the americas than in europe. the model attributed 148,000-249,000 respiratory deaths to influenza in an average pre-pandemic season,with only 19% in persons <65 y. limitations include lack of representation of low-income countries among single-country estimates and an inability to study subsequent pandemic waves (2010-2012).conclusions:we estimate that 2009 global pandemic respiratory mortality was ∼10-fold higher than the world health organization's laboratory-confirmed mortality count. although the pandemic mortality estimate was similar in magnitude to that of seasonal influenza,a marked shift toward mortality among persons <65 y of age occurred,so that many more life-years were lost. the burden varied greatly among countries,corroborating early reports of far greater pandemic severity in the americas than in australia,new zealand,and europe. a collaborative network to collect and analyze mortality and hospitalization surveillance data is needed to rapidly establish the severity of future pandemics.please see later in the article for the editors' summary. © 2013 simonsen et al.