Age-related changes in durability and function of vaccine-elicited influenza-specific CD4+ T-cell responses

► Influenza vaccine (TIV) immunogenicity among young (18-49 years old) and elderly (≥70 years old). ► Vaccine elicits predominantly central memory and effector memory CD4+ T-cells. ► Vaccine-elicited T cell responses are short-lived among the elderly. ► PBMC from younger subjects are superior at producing IFN-γ after short-term Ag-specific culture.