Recall of CD4 T cell memory by SARS-CoV-2 and influenza vaccines

Dr. Juno explores how repeated mRNA vaccination shapes CD4 T cell memory, comparing responses to influenza and SARS-CoV-2 boosters. Researchers found that while influenza vaccination elicited a classic T follicular helper (TFH) recall response, SARS-CoV-2 boosters produced qualitatively distinct CD4 T cell responses that were progressively blunted with repeated doses, yet still supported strong antibody production. Interestingly, SARS-CoV-2–specific CD4 memory cells showed less TFH bias than influenza-specific cells, suggesting fundamental differences in how long-term CD4 memory is maintained. A key enabler of this work was ProImmune’s ProT2® MHC class II tetramer technology, which allowed direct tracking and phenotyping of antigen-specific CD4 T cells ex vivo, validating and extending the AIM assay findings.