Inclusion criteria: (1) were 21 years or younger (2) were hospitalized at Columbia University Irving Medical Center/NewYork-Presbyterian Morgan Stanley Children’s Hospital in New York City between April 18 and May 5, 2020 (3) presented with a clinical syndrome characterized by prolonged fever, systemic inflammation, shock, end-organ dysfunction, or symptoms reminiscent of KD or TSS (4) had evidence of recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, determined by reverse transcriptase–polymerase chain reaction (RT-PCR) of nasopharyngeal swabs or positive serology