Serum S100A8/A9 levels may aid in determining the diagnosis and severity of CAP in children, and S100A8/A9 levels of ≥ 1.246 ng/mL may be a more valuable cut-off value for severe CAP, supporting it as a novel and intriguing biomarker for pneumonia to the monitor children patients’ response and predict the condition, which may have implications for more accurate medical triage decisions. The gene discussed is S100A8; the disease is pneumonia.