1. Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
2. Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
3. California Emerging Infections Program, Oakland, California, USA
4. Colorado Department of Public Health and Environment, Denver, Colorado, USA
5. Connecticut Emerging Infections Program, Yale School of Public Health, New Haven, Connecticut, USA
6. Department of Medicine and Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
7. Georgia Emerging Infections Program, Georgia Department of Health, Atlanta, Georgia, USA
8. Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, USA
9. Maryland Department of Health, Baltimore, Maryland, USA
10. Michigan Department of Health and Human Services, Lansing, Michigan, USA
11. Minnesota Department of Health, St Paul, Minnesota, USA
12. New Mexico Department of Health, Santa Fe, New Mexico, USA
13. New York State Department of Health, Albany, New York, USA
14. University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
15. Ohio Department of Health, Columbus, Ohio, USA
16. Oregon Public Health Authority, Portland, Oregon, USA
17. Vanderbilt University School of Medicine, Nashville, Tennessee, USA
18. Salt Lake County Health Department, Salt Lake City, Utah, USA