CD4 and COVID-19: To ascertain whether similar patterns were maintained in convalescent COVID-19 donors, we compared the frequency of ancestral SARS-CoV-2 spike-, nucleocapsid (N)- and membrane (M)-specific CD4 and CD8 T cells in convalescent COVID-19 patients infected during the first wave with the ancestral strain (n = 10) or during the second wave, when Beta dominated (n = 14) (Fig. 2A).