The primary objective of this study is to determine performance characteristics of the FebriDx® test in differentiating bacterial from non-bacterial etiology among febrile pediatric patients (2-11 years) presenting to the emergency department, urgent care center or primary care office with a suspected acute respiratory tract infection.

This is a prospective, multi-center, observational, blinded study where children with suspected acute respiratory infection will undergo FebriDx® testing.

The primary outcome is the presence of a bacterial associated systemic host immune response related to a febrile acute respiratory tract infection, as compared to the reference standard of clinical adjudication as determined by a panel of pediatric experts using the Clinical Reference Algorithm that includes pathogen detection testing (e.g., bacterial culture, multiplex PCR) as well as measures of host immune response.

FebriDx is a rapid lateral flow immunoassay for the visual, qualitative, in vitro detection of elevated levels of host response proteins, Myxovirus resistance protein A (MxA) and C-reactive protein (CRP), directly from fingerstick blood.

Inclusion Criteria:

• Signed informed consent by parent/guardian and Assent for ages 7-11 years
• Exhibit or report of a new onset measured temperature (oral or tympanic) of greater than or equal to 100.4°F/38°C within 3 days (72 hours) of enrollment
• Clinical suspicion for Acute Respiratory Infection beginning within 7 days before enrollment AND presents with at least one of the following new onset of symptoms: runny nose, nasal congestion, sore throat, cough, hoarse voice, shortness of breath / difficulty breathing

Exclusion Criteria:

• Unwilling to participate in 7-day follow-up or sign HIPAA waiver to obtain medical record if hospitalized
• Immunocompromised state or taking immunosuppressive or chemotherapeutic medications in the last 30 days (e.g. oral / inhaled steroids, Methotrexate, Cyclosporine, Chemotherapy, interferon therapy)
• Taking antibiotics or antiviral therapy in the last 14 days
• Received a live viral immunization in the last 14 days
• Clinical diagnosis of otitis media or recognizable viral syndrome (i.e., croup, varicella, stomatitis) at the time of enrollment
• Prior enrollment in the study

Pediatric patients presenting to the emergency department, urgent care center or primary care office with a suspected acute respiratory tract infection

No individual participant data will be shared.