CHMP5 and COVID-19: Acute adult COVID-19 samples, acute pediatric COVID-19 samples, and MIS-C samples were first analyzed by enzyme-linked immunosorbent assay (ELISA) for seropositivity to SARS-CoV-2 spike protein, with 89 of 109 (82%), 8 of 9 (88.9%), and 20 of 20 (100%) considered seropositive, respectively, by criteria described in the extended Materials and Methods section of the Supplementary Information.