CD27 and Huntington disease: Despite this, pre-germinal center (GC) (CD19+ CD20+/++ CD27− IgMD+) B-cell counts were significantly decreased in the blood of SARS-CoV-2 naïve non-MBL HD, particularly at day +4 after the second dose of the vaccine, which was followed by a rapid increase at day +7 (0.02-fold increase at day 0 vs. 0.63-fold decrease at day +4 vs. 0.12-fold decrease at day +7) (Figure 3).