A donor's response to influenza was considered positive if: a) the frequency of IFNγ+ CD8 T cells was greater than that of stimulation controls, b) the frequency of IFNγ+ cells was greater than 0.01% of the total CD8 T cell pool, and c) the product of the MFI and the frequency of IFNγ+ CD8 T cells was at least two-fold above the control cultures' values. Here, CD8A is linked to influenza.