Multisystem Inflammatory Syndrome after SARS-CoV-2 Infection and COVID-19 Vaccination

M ultisystem infl ammatory syndrome (MIS) in children (MIS-C) and adults (MIS-A) are febrile syndromes with elevated infl ammatory markers that usually manifest 2-6 weeks after a severe acute respiratory syndrome 2 (SARS-CoV-2) infection (1-3). The Brighton Collaboration Case Defi nition for MIS-C/A was recently published to be used in the evaluation of patients after SARS-CoV-2 immunization (3); some scientists are concerned that vaccination against SARS-CoV-2 can trigger MIS-C/A. We report 6 cases of MIS from a large integrated health system in Southern California, USA; 3 of those patients received SARS-CoV-2 vaccination shortly before seeking care for MIS. All 6 patients met the Brighton Collaboration Level 1 of diagnostic certainty for a defi nitive case and had MIS illness onset between January 15-February 15, 2021.