Diagnostic Accuracy of a Host-response Based Diagnostic Tool for Distinguishing Between Bacterial and Viral Etiologies in Pediatric Patients

Inclusion Criteria: * Legal guardian signs an informed consent * Documented peak temperature ≥ 38°C (100.4°F) * Symptom duration ≤ 7 days * Clinical suspicion of RTI (OR) fever without a clear source after clinical examination Exclusion Criteria: * Another episode of febrile infection within the past 2 weeks * Antibiotic treatment of over 48 hours * Congenital immune deficiency (CID) * A proven or suspected HIV, HBV, HCV infection * Active malignancy * Current treatment with immune-suppressive or immune-modulating therapies, including without limitations: * Use of high dose steroids \>1 mg/kg/day prednisone or equivalent in the past two weeks * Monoclonal antibodies, anti-TNF agents * Intravenous immunoglobulin (IVIG) * Cyclosporine, Cyclophosphamide, Tacrolimus * G/GM-CSF, Interferons * Other severe illnesses that affect life expectancy and/or quality of life such as: * Severe psychomotor retardation * Post-transplant patients * Severe congential metabolic disorder