We started our investigation by analyzing F/GC B cell subsets in LD-LNs from COVID-19–infected individuals from 2 centers (CHUV and Northwestern University) (Table 1 and Supplemental Table 1) by applying a mIF (Supplemental Tables 2 and 3) that allows for the simultaneous detection of CD20, Bcl6, and Ki67 (Figure 1 and Supplemental Figure 1). This evidence concerns the gene MKI67 and COVID-19.