Dear Editor,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is more likely to progress to severe disease in the elderly, and the rates of hospitalization for coronavirus disease 2019 (COVID-19) increase with age. 1,2Herein, we comprehensively compared adaptive and innate immune responses between children and adults infected with SARS-CoV-2.A total of 57 children and 57 adult patients with confirmed SARS-CoV-2 infection were enrolled in this study.Disease severity was determined according to the NIH severity of illness categories: asymptomatic, mild, moderate, severe, and critical. 3In the current study, we grouped patients into three categories: asymptomatic, non-severe (mild and moderate), and severe (severe and critical).Thus, this study included 14 asymptomatic children, 43 non-severe children, 30 non-severe adults, and 27 severe adults, and we compared various immunological parameters among these four groups, particularly between non-severe children and adult groups.Clinical information is presented in Supplementary Table 1.