Serum amounts of IgG subclasses (A–D), IgM (E), and IgA (F) of patients with CAP caused by SARS-CoV-2 are shown. Patients are classified into three states of immune activation: intermediate, dysregulation, and MAS. Findings are compared with those in patients with bacterial CAP, who are classified into three states of immune activation: intermediate, immunoparalysis, and MAS.