CD4 and COVID-19: The frequency of CD4+OX40+41BB+ T cells trended lower in participants with MIS-C compared with convalescent COVID-19 following spike MP stimulation (P = 0.055) and was significantly reduced after non-spike MP stimulation (P = 0.01) (Figure 1B), with a lower total CD4+OX40+41BB+ T cell frequency (sum of spike and non-spike responses) in MIS-C versus convalescent COVID-19 (P = 0.02) (Figure 1C).