Moreover, current mRNA-based COVID-19 vaccines are known to induce strong poly-specific T-cell responses mediated by IFN+ or IL-2+ CD8+ and CD4+ Th1-cells (45), which have been shown to present higher durability (46–48) and cross-reactivity (49–51) against CoV-2 variants than serum neutralizing antibody responses. This evidence concerns the gene IL2 and COVID-19.