CD79A and COVID-19: S IgG and IgA responses were robust in most COVID-19 cases (25/28 acute, 15/15 convalescent S IgG; Figures 1E and S1E) (27/28 acute, 14/15 convalescent S IgA; Figures 1F and S1F), though ∼17% of cases had relatively low titers (within 3-fold of the LOD).