[1] CDC, Off Genom & Dis Prevent, Coordinating Ctr Hlth Promot, Atlanta, GA 30341 USA
[2] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[3] Univ Washington, Dept Pediat, Seattle, WA 98195 USA
[4] Kaiser Permanente No Calif, Vaccine Study Ctr, Oakland, CA USA
[5] Hlth Partners Res Fdn, Minneapolis, MN USA
[6] Harvard Pilgrim, Boston, MA USA
[7] Harvard Vanguard, Boston, MA USA