About the Authors

Marc Lipsitch

To whom correspondence should be addressed. E-mail: mlipsitc@hsph.harvard.edu

Affiliations Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America , Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America

Ted Cohen

Affiliations Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America , Division of Social Medicine and Health Inequalities, Harvard Medical School, Boston, Massachusetts, United States of America

Megan Murray

Affiliations Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America , Division of Social Medicine and Health Inequalities, Harvard Medical School, Boston, Massachusetts, United States of America , Division of Infectious Diseases and General Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America

Bruce R Levin

Affiliation Department of Biology, Emory University, Atlanta, Georgia, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

ML and BRL designed the study and analyzed the data, following conversations involving all four authors. All authors contributed to writing the paper.