Apart from CD8+ T cells, we also identified influenza-specific CD4+ T cells in 5/5 H3N2-infected patients with either HLA-DR*01:01-, DR*04:01- or DR*11:01-HA-tetramers (Fig. 6e, f), despite ~10-fold lower numbers of antigen-specific CD4+ T cells ex vivo. Here, CD4 is linked to influenza.