,26,27 While all vaccinated groups induced an S-specific CD8+ T cell response (Figures 2D and 2E), boosting with the bivalent mRNA vaccine induced higher frequency of CD8+ T cell responses compared to an infection with SARS-CoV-2 XBB.1.5 or primary vaccination (Figures 2D and 2E). This evidence concerns the gene CD8A and infection.