1 Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH Biostatistics Core, The Research Institute at Nationwide Children's Hospital, Columbus, OH Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH, Division of Pediatric Infectious Diseases, Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH, Division of Pediatric Infectious Diseases, Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH.