FACS-based immunophenotyping, confirmed higher frequencies of the memory CD8+ TEM (CD44+CD62L −) cell subset in immunized mice with a pool of pan- coronavirus peptides and subjected to infection against USA-WA1/2020 (Vaccinated = 12.2% vs. Mock = 5%, p < 0.0001), Alpha (B.1.1.7) (Vaccinated = 6.5% vs. Mock = 3.7%, p = 0.0017), Beta (B.1.351) (Vaccinated = 7.2% vs. Mock = 3.4%, p = 0.0253), and Omicron (B.1.1.529) (Vaccinated = 5.9% vs. Mock = 3%, p = 0.9765) (Figure 4C). This evidence concerns the gene CD8A and infection.