CR2 and COVID-19: Compared to controls, COVID-19 cases displayed a considerably shrunken follicular B-cell compartment (paucity of germinal centers, see above) with a disruption of CD21-positive follicular dendritic cell (FDC) networks (19/21 disrupted in COVID-19 vs. 11/14 in controls; p<0.001) (Figures 1B and 3), while showing a median of 15% of MUM1p-positive plasmablasts compared to 5% in controls (p=0.001) (Figure 3); these plasmablasts expressed mainly IgM and IgG, and the amount of IgA-positive plasmablasts and plasma cells was decreased in COVID-19 (data not shown).