1. Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California (C.Z., I.A.L., L.S.S., W.C., L.Q., D.S.R., S.S.K., C.M., S.J.J.)
2. Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, Georgia (J.D.)
3. Kaiser Permanente South Bay Medical Center, Harbor City, California (R.A.N.).