CD4 and COVID-19: To confirm that COVID-19 mRNA vaccination induces spike-specific CD4+ and CD8+ T cells in patients with IBD undergoing immune-modifying therapy, PBMCs collected on day 115 from patients with IBD were stimulated with a spike peptide megapool (SP-MP) and analyzed for expression of activation-induced markers (AIMs) on gated CD4+ and CD8+ T cells (Figure 5A).