CD8A and infection: However, when the T-cell response was evaluated by previous SARS-CoV-2 infection, a clearly diminished response in CD4+ and CD8+ T cells was observed after the second BTN162b2 dose between the naïve and SARS-CoV-2 previously infected participants; this same behavior of the T cells was observed in a recent study in which a poorly T-cell response was reported in the vaccinated population with the previous infection, denominated by the author as a muted T cells [23].