CD8A and infection: Analysis of influenza-specific CD8+ T-cell numbers showed significant reductions in epitope-specific CD8+ T-cells for 9 out of 11 specificities (NP39–47, PA130–138, PB12–10, PB1216–224, PB1496–505, PB1498–505, PB2322–330, PB2703–710 and PB2549–559) following secondary infection (Supplementary Fig. 3).