Comparison of V heavy and light chain usage within S+ Bm cell subsets in the scRNA-seq data from SARS-CoV-2-recovered individuals (months 6 and 12 post-infection) revealed very similar chain usage in S+ CD21+ resting (CD21+CD27+ and CD21+CD27– combined), CD21–CD27+CD71+ activated and CD21–CD27–FcRL5+ Bm cells (Extended Data Fig. 9a). The gene discussed is TFRC; the disease is infection.