About the Authors

Martha I. Nelson

Affiliation Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America

Cécile Viboud

Affiliation Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America

Lone Simonsen

Affiliation Department of Global Health, School of Public Health and Health Services, The George Washington University, Washington, D.C., United States of America

Ryan T. Bennett

Affiliation Wadsworth Center, New York State Department of Health, Albany, New York, United States of America

Sara B. Griesemer

Affiliation Wadsworth Center, New York State Department of Health, Albany, New York, United States of America

Kirsten St. George

Affiliation Wadsworth Center, New York State Department of Health, Albany, New York, United States of America

Jill Taylor

Affiliation Wadsworth Center, New York State Department of Health, Albany, New York, United States of America

David J. Spiro

Affiliation The J. Craig Venter Institute, Rockville, Maryland, United States of America

Naomi A. Sengamalay

Affiliation Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America

Elodie Ghedin

Affiliation Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America

Jeffery K. Taubenberger

Affiliation Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America

Edward C. Holmes

ech15@psu.edu

Affiliations Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America, Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: MN EH. Performed the experiments: RB SG KS JT DS NS EG. Analyzed the data: MN. Wrote the paper: MN CV LS RB SG KS JT DS NS EG JKT EH. Performed the sequence analysis: MN. Advised on epidemiological aspects of the study: CV LS. Collected a subset of the viral samples: RB SG KS JT. Undertook the viral genome sequencing: DS NS EG. Advised on virological aspects of the study: JKT.