SDC1 and Huntington disease: These different PC kinetic profiles were associated with overall higher CD138−, IgM+, and IgG+ PC counts (including all IgG subclasses) in the blood of SARS-CoV-2 naïve vs. previously infected non-MBL HD at the later time points investigated (i.e., days +10 and +30 after the second dose) (Figure 4 and Supplementary Figure S4).