As a consequence of the delay in reaching the PC peak in SARS-CoV-2 naïve vs. previously infected subjects, a (low) tendency towards higher total PC and IgG+ PC counts were found at day +7 for the latter group, whereas higher total PC and IgG+ PC counts, due to both the IgG1+ and IgG3+ PC counts (Supplementary Figure S4), were observed in the blood of SARS-CoV-2 naïve non-MBL HD at day +10 (Figure 4). This evidence concerns the gene IGHG3 and Huntington disease.