COVID-19 mRNA booster vaccine induces transient CD8+ T effector cell responses while conserving the memory pool for subsequent reactivation

Vaccines induce beneficial immunity for COVID-19, but immune waning prompts boosting vaccination. Here, the authors show that a third, boosting dose of COVID-19 mRNA vaccine induces transient CD8 + T effector cell response while conserving the CD8 memory T cell pool, thereby permitting reactivation of spike-specific CD8 + T cells upon breakthrough infection or 4th vaccination.