1. aInfluenza Division, US Centers for Disease Control and Prevention, Atlanta, Georgia
2. bTexas A&M University Health Science Center College of Medicine, Temple, Texas
3. cBaylor Scott & White Health Research Institute, Temple, Texas
4. dKaiser Permanente Washington Health Research Institute, Seattle, Washington
5. eSchool of Public Health, University of Michigan, Ann Arbor, Michigan
6. fSchool of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
7. gMarshfield Clinic Research Institute, Marshfield, Wisconsin