1. aDivision of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
2. bDivision of Infectious Diseases, Department of Pediatrics, Boston Children’s Hospital, Boston, Massachusetts
3. cHarvard Medical School, Boston, Massachusetts
4. dDivision of Infectious Diseases, Department of Pediatrics, Seattle Children’s Hospital, Seattle, Washington