1. From the Department of Pediatrics (K.J.B., W.E., H.V.A., T.C.S., T.J.S.) and the Division of Infectious Diseases (K.J.B., W.E., H.V.A., T.C.S., T.J.S.), Boston Children’s Hospital, the Department of Pediatrics, Boston Medical Center (K.J.B., W.E.), and the Department of Pediatrics, Harvard Medical School (K.J.B., W.E., H.V.A., T.J.S.) — all in Boston.