CD40LG and COVID-19: COVID-19 was identified by throat/nasal swabs SARS-CoV-2 PCR in 14 (11.4%) at the time of hospitalization due to MIS-C; both IgM and IgG antibodies against SARS-CoV-2 virus were positive in 29 (23.6%), as well as only IgG in 105 (85.4%).