Given that monocytes had the largest number of transcriptional differences in our scRNA-seq, we sought to analyze their chromatin accessibility using the assay for transposase-accessible chromatin sequencing (ATAC-seq) on CD14+ monocytes enriched from PBMCs of hospitalized patients with COVID-19 over the 2-week follow-up (Fig. 1). Here, CD14 is linked to COVID-19.