CD40LG and common variable immunodeficiency: In our longitudinal study, in the CVID patients, total B cells were decreased following the 1st dose and recovered after the 2nd dose of the vaccine that was shared by a decrease in naïve B cells and transition B cells and an increase in IgM memory and CSM B cells, plasmablasts, and CD21low B cells, suggesting a migration of B cells from the peripheral blood to lymphoid follicles and undergoing differentiation to memory and plasmablasts.