1. Brigham and Women's Hospital, Boston, Massachusetts, USA;
2. Northwestern University, Chicago, Illinois, USA;
3. Memorial Sloan-Kettering Cancer Center, New York, New York, USA;
4. Washington University School of Medicine, St. Louis, Missouri, USA;
5. Centers for Disease Control and Prevention, Atlanta, Georgia, USA;
6. Johns Hopkins Medical Institutions, Baltimore, Maryland, USA;
7. North Shore Medical Center-Salem Hospital, Salem, Massachusetts, USA;
8. Massachusetts General Hospital, Boston, Massachusetts, USA;
9. Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA;
10. Mount Auburn Medical Center, Cambridge, Massachusetts, USA;
11. University of Iowa Carver College of Medicine, Iowa City, Iowa, USA;
12. McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA;
13. Harvard Pilgrim Health Care, Boston, Massachusetts, USA