1. Department of Epidemiology, University of Michigan School of Public Health , Ann Arbor, Michigan , USA
2. Westat , Rockville, Maryland , USA
3. Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention , Atlanta, Georgia , USA
4. Division of Immunizations, Michigan Department of Health and Human Services , Lansing, Michigan , USA
5. Marshfield Clinic Research Institute , Marshfield, Wisconsin , USA
6. Department of Internal Medicine, University of Michigan Medical School , Ann Arbor, Michigan , USA