CD4 and COVID-19: To investigate T cell changes in our cohort, we first characterized T cell activation as determined by dual expression of HLA-DR and CD38, previously shown to be upregulated in severely infected COVID-19 patients (2), and found that the CD4+ T cell population had increased HLA-DR+CD38+ expression when comparing early and intermediate time points, as well as when comparing the early time point with CoV– controls (Figure 2A; P = 0.024 and P = 0.021, respectively).