Upon comparing both groups of non-MBL HD, significantly higher CD21- MBC (CD19+ CD20++ CD5− CD27−/+ IgMD−/+) counts were found at day +30 after the second dose in blood of previously infected non-MBL HD (0.40-fold increase vs. 0.60-fold decrease in SARS-CoV-2 naïve non-MBL HD) (Figure 3 and Supplementary Figure S2). This evidence concerns the gene CD19 and Huntington disease.