1. Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia.
2. Department of Infectious Diseases, Brown University, Providence, Rhode Island.
3. University of Alabama at Birmingham School of Medicine, Birmingham, Alabama.
4. Hennepin County Medical Center, University of Minnesota, Minneapolis, Minnesota.
5. Washington University School of Medicine, St. Louis, Missouri.
6. Abbott-Northwestern Hospital, Minneapolis, Minnesota.
7. Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia.