IL6 and lymphopenia: (1) Age of onset: <21 years; (2) Clinical features: Fever >38.0°C for ≥24 hours or subjective fever for ≥24 hours, alongside dysfunction in ≥2 organ systems (gastrointestinal, respiratory, cardiovascular, renal, hematological, dermatological, or neurological); (3) Laboratory findings: Including, but not limited to, one or more of the following: elevated CRP, procalcitonin, ESR, ferritin, interleukin-6, neutrophilia, lymphopenia, and hypoalbuminemia; (4) SARS-CoV-2 infection/exposure within 4 weeks (10).