1. Vanderbilt University Medical Center, Nashville, Tennessee
2. University of Rochester School of Medicine and Dentistry, New York
3. Mattel Children’s Hospital at University of California at Los Angeles
4. Cincinnati Children’s Hospital Medical Center, Ohio
5. Emory University, Atlanta, Georgia
6. National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
7. University of Pittsburgh School of Medicine, Children’s Hospital of Pittsburgh of UPMC, Pennsylvania