Additional validation groups (Supplementary Methods and eTable 1 in the Supplemental Appendix) included children with meningococcal sepsis,16 inflammatory diseases (Juvenile Idiopathic Arthritis and Henoch-Schönlein purpura) and published gene expression datasets which compared bacterial infection with viral infection,12 (link),15 (link),17 (link) or inflammatory disease.18 (link) Healthy children were recruited from out-patient departments. Data from healthy controls were not utilized in identification or validation of gene expression signatures, and were only used for interpretation of direction of gene regulation.