A line list will be created for all potential cases of GBS. For adjudicated cases of GBS, the listing will indicate the final case status, elements of the case definition that were and were not met, immunization status (MCV4, MPSV4, Tdap, Td, HepB, HPV, tetanus, and influenza) and indicators of infection or febrile illness in the prior 42 days, gender, age, month and year of GBS onset, and a brief description of disease severity. Additional line lists will be created for censored cases (adjudicated non-cases) that include the reason for censoring, and for potential cases for which charts could not be obtained or insufficient information was obtained from the chart to adjudicate case status.