PDCD1 and COVID-19: To further examine the SARS-CoV-2-specific CD8 T cells, we measured the expression levels (ex vivo) of the inhibitory receptors NKG2A and programmed cell death protein 1 (PD-1) on SARS-CoV-2-specific CD8 T cells compared to bulk CD8 T cells from COVID-19 patients with acute disease.