HP and COVID-19: The authors showed that the increased permeability of the mucosal barrier triggered by zonulin matched well with the SARS-CoV-2 antigenemia (SARS-CoV-2 spike protein, especially S1 region, and nucleocapsid antigens identified in the plasma of patients with MIS-C, a few weeks after infection or initial contact with SARS-CoV-2), which was significantly increased in patients with MIS-C compared to healthy controls or children with acute COVID-19.