CD69 and COVID-19: Dimensional reduction using Uniform Manifold Approximation and Projection (UMAP) showed distinct clustering of SARS-CoV-2 multimer-reactive T cells of the COVID-19 patient cohort compared to the two healthy donor cohorts with higher expression of activation markers CD38, CD69, CD39, HLA-DR, CD57, and reduced expression of CD8 and CD27 (Fig. S6).