febrile infants Other respiratory viral testing may also be informative as febrile infants younger than 60 days with influenza have lower risk of serious bacterial infections but still have substantial risk of UTI Biomarkers, including procalcitonin and C-reactive protein, have been recently evaluated as predictors of serious bacterial infection in febrile young infants and may help to identify populations at low risk for serious bacterial infection Recent studies have suggested that incorporating procalcitonin into the laboratory evaluation of the young febrile infant may improve diagnostic accuracy of bacterial infection Further evaluations of these markers alone and in combination with existing algorithms are needed to determine if they will provide improved prediction of serious bacterial infection in newborns and young infants