We would like to express our gratitude to the people of Dirección General de Epidemiología, the Peruvian national network of epidemiology and the laboratory and database personnel of US NAMRU-6 in Peru for all their hard work during the 2009 A/H1N1 influenza pandemic. We also thank Kamal Barely for assistance with graphic enhancement. This research was conducted in the context of the Multinational Influenza Seasonal Mortality Study (MISMS), an on-going international collaborative effort to understand influenza epidemiological and evolutionary patterns, led by the Fogarty International Center, National Institutes of Health (http:// www.origem.info/misms/index.php).