The ChAdOx1 vaccine induces a Th1-biased response characterized by IFN-γ and TNF-α secretion by CD4+ T cells, predominant IgG1/IgG3 production, and CD8+ T cells with cytotoxic potential (148), and has demonstrated efficacy against symptomatic infection by the ancestral SARS-CoV-2 strain (149). This evidence concerns the gene CD4 and infection.