CD4 and inflammatory bowel disease: Booster (third-dose) vaccination assessed after 1–3 months was noted to exert similar degrees of activation of CD4/8+ T cells, as well as cTFH subsets associated with further increased anti-Spike IgG titers in IBD patients; however, those on anti-TNF continue to exhibit lower vaccine-induced antibody titers than donors on other biologics [71], likewise seen in a separate study looking at responses 5 months post boost [72].