CD8 T cell differentiation & clinical significance – COVID-19 mRNA vaccination

Prof. Shin describes how COVID-19 mRNA vaccination shapes CD8+ T cell differentiation and durability. Researchers showed that after two doses, stem-cell–like memory T cells expanded and were strongly associated with long-term immune durability, though their generation declined with age. Repeated mRNA boosting (third and fourth doses) enhanced T cell frequency and function but also drove progressive terminal differentiation and senescence, reducing proliferative potential over time. A crucial enabler of this work was ProImmune’s Pro5® MHC Class I Pentamers, which allowed direct ex vivo tracking of antigen-specific CD8+ T cells and detailed analysis of their phenotype, function, and long-term fate.