CD4 and COVID-19: T follicular helpher cells (Tfh) are vital in B cell maturation and immunoglobulin class switching within the germinal centre (5), Two studies have suggested that circulating Tfh (cTfh) from recovered COVID-19 patients include spike-specific CD4 T, but in one study RBD-specific cTfh were rare (14) while in the other, total spike-specific cTfh were only seen in 3/26 subjects (64), overall consistent with a large proportion of immunodominant epitopes for the spike-specific CD4 T cells being outside the RBD (14, 65).