CD19 and COVID-19: In comparison with the 21 patients diagnosed during the same period but without prior vaccination, these patients had higher percentages of the CD19+ B cell subset (p = 0.04, Supplemental Table S3), and patients with a prior COVID-19 vaccination tended to have lower IL-6 (p = 0.09), TNF-α (p = 0.07) and IL-8 levels (p = 0.08).