CD19 and COVID-19: At admission to study (one month after the 3rd vaccine dose, ChAdOx1 nCoV-19/ChAdOx1 nCoV-19/BNT162b2 scheme, and 4 months before COVID-19 hospitalization), he had CD4+ T = 202 cells/mm3, CD8+ T = 79 cells/mm3, CD19+ = 6 cells/mm3.