1. Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia
2. Kaiser Permanente Washington Health Research Institute, Seattle, Washington
3. Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor
4. Marshfield Clinic Research Institute, Marshfield, Wisconsin
5. Baylor Scott and White Health, Texas A&M University Health Science Center College of Medicine, Temple
6. University of Pittsburgh Schools of Health Sciences, Pennsylvania
7. University of Pittsburgh Medical Center, Pennsylvania
8. Vanderbilt University Medical Center, Nashville, Tennessee
9. Department of Medicine, University of Rochester Medical Center, New York