CD79A and COVID-19: Another study of COVID-19 patients admitted to hospital showed that (i) IgA antibodies to SARS-CoV-2 RBD were detected earlier in serum than IgG antibodies; (ii) a large proportion of plasmablasts synthesizing IgA in the blood express chemokine receptor 10 (CCR10), which is a marker for their homing to mucosal sites; (iii) neutralizing IgA anti-RBD antibodies were more abundant in saliva than serum, and were formed early during the onset of symptoms; and (iv) neutralizing IgA antibodies remained detectable in saliva for 49 to 73 days after symptom onset [25].