Previously, we investigated the impact of repeated annual vaccination upon preexisting influenza-specific CD8+ and CD4+ T cells prior to two consecutive influenza seasons in HCWs who were either repeatedly vaccinated or only received a pandemic vaccination.12 In the current study, we further explored the impact of annual vaccination on T cells, particularly CD4+ T cells, and humoral immunity by assessing paired pre- and postvaccination T cell, antibody, and memory B-cell (MBC) responses in repeatedly vaccinated HCWs over 5 years. Here, CD4 is linked to influenza.