To perform an in-depth examination of Tregs and Tfr in humans, we reanalyzed our previously published human peripheral blood mononuclear cell (PBMC) dataset examining a large longitudinal cohort of patients with severe COVID-19 and patients with bacterial sepsis alongside a health care worker cohort of Pfizer mRNA vaccine recipients (23) to focus on Treg subset phenotypes (Fig. 1, A and B). This evidence concerns the gene TFRC and COVID-19.