FCRL5 and COVID-19: Among DN cells, DN1 (FcRL5- CXCR5+) B cells were the dominant subset in both groups of recovered COVID-19 patients, and we did not detect significant differences in the frequencies of DN1, DN2 (FcRL5+ CXCR5-), and DN3 (FcRL5- CXCR5-) B cells between the two groups (Fig 2D, S1B Fig).