CD8A and infection: (2) When combined with the Spike antigen, these T cell PanCoVax vaccine candidates provided an additive or synergistic protective efficacy against infection with Delta and re-infection with Omicron, by promoting cross-protective CD4+ and CD8+ T cells (against non-Spike antigens) and broadly neutralizing antibodies (nAb, against Spike), suggesting that multi-antigen PanCoVax vaccines have the potential to terminate infection before transmission and cross-protect against new variants, other HCoV, and future CoV zoonoses [79].