Lu W, Yang L, Li X, et al. - Researchers conducted a retrospective study of 121 children with COVID-19 with the aim to determine the immune characteristics of early SARS-CoV-2 infection in children and possible key prognostic factors for early detection of critical COVID-19. They statistically analyzed peripheral blood lymphocyte subset counts, T cell-derived cytokine concentrations, inflammatory factor concentrations, and routine blood counts at the initial presentation. Per findings, the valuable indices for early diagnosis of severe disease include reduction T, Th, Tc, RBC, hemoglobin and increase in IL-6 and IL-10 in early SARS-CoV-2 infection in children. At this stage, the significantly reduced Th and Tc cells and significantly increased IL-6, IL-10, ferritin, procalcitonin, and SAA in children with critical COVID-19 may be closely linked with the systemic cytokine storm induced by immune dysregulation.