CD8A and chronic kidney disease: The proportion of IFNy producing CD8+ T-cells of total memory CD8+ cells increased from 0.0012 (IQR 0–0.0144)% in CKD patients and 0.0150 (IQR 0.0034–0.0265)% in controls after the first vaccine dose to 0.0231 (0.0107–0.0397)% and 0.1980 (IQR 0.0930–0.2763)% respectively following dose two (p < 0.001, p < 0.01).