1. Influenza Division, National Center for Immunization and Respiratory Disease, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
2. UPMC Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
3. University of Missouri—Kansas City School of Medicine, Children’s Mercy—Kansas City, Kansas City, Missouri, USA
4. Department of Pediatrics, Seattle Children’s Hospital, Seattle, Washington, USA
5. Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
6. Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
7. Department of Pediatrics, UCLA Mattel Children’s Hospital, Los Angeles, California, USA
8. Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
9. Texas Children’s Hospital, Houston, Texas, USA
10. Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
11. Department of Infectious Diseases, UCSF Benioff Children’s Hospital Oakland, Oakland, California, USA
12. Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
13. Department of Pediatrics, University of Cincinnati College of Medicine, Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
14. Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
15. Baylor Scott and White Health, Texas A&M University College of Medicine, Temple, Texas, USA