CD4 and COVID-19: The PBMCs primed with the epitopes of the current study indicated that COVID-19 recovered and vaccinated PBMCs had a significant increase in the percent of CD4+ and CD8+ T cells with the increased IL2 and IFN- g secretions [(Fig. 5; Suppl Figs. 3,4 & 5, Table 2A, Table 2B A&B)].