[1] Kaiser Permanente, Vaccine Study Ctr, Oakland, CA 94612 USA
[2] Univ Cincinnati, Childrens Hosp, Ctr Global Hlth, Cincinnati, OH USA
[3] Univ Calif San Francisco, Dept Pediat, San Francisco, CA 94143 USA
[4] Permanente Med Grp Inc, San Francisco, CA USA
[5] Kaiser Permanente, Div Res, Oakland, CA USA
[6] Ctr Dis Control & Prevent, Atlanta, GA USA